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Linux Gazette... making Linux just a little more fun!
Copyright © 1996-97 Specialized Systems Consultants, Inc.
linux@ssc.com
_________________________________________________________________
Welcome to Linux Gazette! (tm)
Linux Gazette, a member of the Linux Documentation Project, is an
on-line WWW publication that is dedicated to two simple ideas:
* Making Linux just a little more fun
* Sharing ideas and discoveries
The basic idea behind these two concepts is that Linux is one cool OS,
whose price for admission is a willingness to read, learn, tinker
(aka, hack!), and then share your experiences. The Gazette is a
compilation of basic tips, tricks, suggestions, ideas and short
articles about Linux designed to make using Linux fun and easy. LG
began as a personal project of John M. Fisk, and grew to include
contributions freely provided by a growing number of authors. Linux
Journal is now publishing the Gazette using material contributed by
outside authors (note to potential authors). Without these authors
there would not be a Gazette, and I thank them all. Drop a note to the
author of anything that you find helpful or instructive--the author's
e-mail address is included for this very purpose.
Linux Gazette is a non-commercial publication and will remain that
way. A tar, gzip file containing all issues of Linux Gazette and one
containing the current issue can be found at ftp://ftp.ssc.com/pub/lg/
Thanks to Matt Welsh, coordinator of the Linux Documentation Project,
for graciously bringing the Linux Gazette under the auspices of the
LDP. The material included in these documents is covered by a
designedly liberal copyright. For information regarding copying and
distribution of this material read the Copying License.
A new table of contents will appear with each issue that will allow
you to easily find articles of interest. A search engine is also
provided to allow you to search all issues for items relating to a
particular subject.
Have fun!
_________________________________________________________________
* Table of Contents Issue #13
* Table of Contents Issue #12
* Table of Contents Issue #11
* Table of Contents Issue #10
* Table of Contents Issue #9
* Table of Contents Issues #1-#8
* Index of All Issues
_________________________________________________________________
Search In: [Linux Gazette (TM).......]
Search For: ______________________________ ______
_________________________________________________________________
Linux Gazette WWW & FTP Mirror Sites
For those readers who are accessing Linux Gazette from outside the
U.S. or are having problems with slow connections at a particular
site, mirror sites are available worldwide. Thanks to all of the
people who have kindly offered the use of their WWW and FTP sites in
order to make this possible!
_________________________________________________________________
Linux Journal's latest -->
HOT LINUX NEWS!
_________________________________________________________________
-->
LINUX INFORMATION
Two SSC links that you might find useful. The first is to Linux
Journal 's "Hot Linux News" page, and the second is to SSC's Linux
Resources page.
_________________________________________________________________
LINUX GAZETTE IS PUBLISHED BY:
SSC - Publishers of Linux Journal (tm)
_________________________________________________________________
Got any great ideas for improvements! Send your comments, criticisms,
suggestions and ideas.
Linux Gazette, http://www.ssc.com/lg/
This page written and maintained by the Editor of Linux Gazette,
gazette@ssc.com
_________________________________________________________________
_________________________________________________________________
LINUX GAZETTE
Copyright © 1997 Specialized Systems Consultants, Inc.
For information regarding copying and distribution of this material see
the Copying License.
_________________________________________________________________
TABLE OF CONTENTS ISSUE #13
_________________________________________________________________
* The Front Page
* The MailBag
+ Help Wanted -- Article Ideas
+ General Mail
* More 2 Cent Tips
+ Another 2cent Tip for LG
+ Console Trick Follow-up
+ GIF Animations
+ How to close and reopen a new /var/adm/messages file
+ How to truncate /var/adm/messages
+ Info-ZIP encryption code
+ Kernel Compile Woes
+ Letter 1 to LJ Editor re Titlebar
+ Letter 2 to LJ Editor re Titlebar
+ PPP redialer script--A Quick Hack
+ TABLE tags in HTML
+ Text File undelete
+ Truncating /var/adm/messages
+ 2c Host Trick
+ Use of TCSH's :e and :r Extensions
+ Various notes on 2c tips, Gazette 12
+ Viewing HOWTO Documents
+ Xaw-XPM .Xresources troubleshooting tip
+ Xterm Titlebar
* News Bytes
+ News in General
+ Software Announcements
* The Answer Guy, by James T. Dennis
+ Dialup Problem
+ File Referencing
+ Combining Modems for More Speed
+ WWW Server
* Comdex '96, by Belinda Frazier & Kevin Pierce
* Filtering Advertisements from Web Pages using IPFWADM, by David
Rudder
* Floppy Disk Tips, by Bill Duncan
* Graphics Muse, by Michael J. Hammel
+ History of Portable Network Graphics Format, by Greg Roelofs
* Indexing Texts with Smart, by Hans Paijmans
* Linux Text Editors and A New One, by Oleg L. Machulskiy
* New Release Reviews, by Larry Ayers
+ Two New X Windows Mail Clients
+ Miscellaneous Notes
* Petition to Cancel Filed Against Linux Trademark
* SLEW: Space Low Early Warning, by James T. Dennis
* The Back Page
+ About This Month's Authors
+ Not Linux
Weekend Mechanic
will return next month.
_________________________________________________________________
TWDT 1 (text)
TWDT 2 (HTML)
are files containing the entire issue: one in text format, one in
HTML. They are provided strictly as a way to save the contents as one
file for later printing in the format of your choice; there is no
guarantee of working links in the HTML version.
_________________________________________________________________
Got any great ideas for improvements! Send your comments, criticisms,
suggestions and ideas.
_________________________________________________________________
This page written and maintained by the Editor of Linux Gazette,
_________________________________________________________________
"Linux Gazette...making Linux just a little more fun!"
_________________________________________________________________
The Mailbag!
Write the Gazette at gazette@ssc.com
CONTENTS:
* Help Wanted -- Article Ideas
* General Mail
_________________________________________________________________
HELP WANTED -- ARTICLE IDEAS
_________________________________________________________________
Date: Sun, 17 Nov 1996 18:49:56 -0600
Subject: a reply type thing...
From: Glenn E. Satan, insipid@onramp.net
> Subject: Xwindows depth
> From: James Amendolagine uq274@freenet.victoria.bc.ca
>
> I have recently been messing with my x-server, and have managed
> to get a depth of 16, ie 2^16 colors. This works
> really nice with Netscape, but some programs (doom, abuse, and
> other games) wont work with this many colors. Do
> you know of a fix? I have tried to get X to support multiple
> depths--to no avail. The man-page suggests that some
> video cards support multiple depths and some don't. How do I know
> if mine does.
>
> I would really like to see an article on this subject,
I would like to say, yes, please someone help.... thought maybe a
reply would motivate someone a little more to write a article on this.
(All right a second request for help in this area. Anybody out there
with suggestions and/or wanting to write an article? --Editor)
_________________________________________________________________
Date: Sun, 01 Dec 1996 00:20:12 +1000
Subject: Quilting and geometry
From: Chris Hennessy, chenness@enterprise.powerup.com.au
I liked your comment about quilting being an interest. We tend to
forget that people have interests outside of computers in general (and
linux in particular).
Just like to say thanks for what is obviously an enormous effort you
are putting into the gazette. I'm new(ish) to linux and I find it a
great resource, not to say entertaining.
Has anyone suggested an article on the use of Xresources? As I said
I'm fairly new and find this a bit confusing... maybe someone would be
interested in an example or three?
Oh and with the quilting and geometry ... better make sure its not the
80x25+1-1 variety.
(Thanks, LG is a lot of work, as well as a lot of fun. And yes, I do
have a life outside of Linux. Anyone interested in writing about
Xresources? Thanks for writing. It's always nice to know we are
attracting new readers. --Editor)
_________________________________________________________________
Date: Wed, 4 Dec 1996 13:33:26 +0200 (EET)
Subject: security issue!
From: Arto Repola, arepola@raahenet.ratol.fi
Hi there!
I was wondering that could you write in some Gazette something about
Linux security...how to improve it, how to setup firewall,shadow
password systems etc?
I'm considering to build up my own linux-server and i really would
like to make it as secure as possible!
Nothing more this time!
http://raahenet.ratol.fi/~arepola
(And another great idea for an article. Any takers? --Editor)
_________________________________________________________________
Date: Wed, 04 Dec 1996 08:08:06 -0700
Subject: Reader Response
From: James Cannon, cannonj@jads.kirtland.af.mil
Organization: JADS JTF
Great Resource,
I really like the resource Linux offers new users. I have already
applied a few tricks to my PC. I wish some one would explain how to
use the GNU C/C++ compiler with Linux. It is a tool resting in my hard
drive. With commercial compilers, there is a programming environment
that links libraries automatically. Are there any tricks to command
line C/C++ programming with Linux?? Stay online!
James Cannon
(Thanks for the tip. Online is the best place to be. Anyone out
there got some C++ help for this guy? --Editor)
_________________________________________________________________
Date: Mon, 9 Dec 1996 23:27:21 +0000 (GMT)
Subject: Linux InfraRed Support
From: Hong Kim, kimh@domp04.adm.intelsat.int
Hi,
I have been so far unsuccessful in finding information for InfraRed
support on Linux.
I am particularly interested in hooking up Caldera Linux on a Thinkpad
560 using Extended Systems JetEye Net Plus. Caldera on Thinkpad I can
handle but the JetEye allows connection to ethernet or token ring
networks via IR.
My searches of Linux Resources page come up negative. I have posted to
USENET and also emailed any web master that has any mention of
ThinkPad or IR on their pages. Still no answer.
Can you help me to find information. If I am successful, I would be
willing to write an article about it.
Hong
(I have sent your question on to Linux Journal's Tech Support
Column. Answers from this source can be slow as author contacts
companys involved. Sounds like you have covered all the bases in
your search -- can anyone out there help him? If you write the
article, I'll be happy to post it in the LG so next person who
needs this information will have a quicker answer. --Editor)
_________________________________________________________________
Date: Thu, 5 Dec 96 13:00:01 MET
Subject: Linux networking problem ...
From: Tauche%fbm%mfh@mfhdvzis.mfh-iserlohn.de
Hi there,
First I have to apologize for writing to this address with my problem,
but I don't no where to search for an answer and university's network
is so damned slow that surfing through the net searching for an answer
makes no fun. Another reason is that I've got no access to Usenet...
means can't post in comp.os.linux.networking... 8-((
I tried to find a news server near to Germany which allows posting
without using that damned -> identd Here's the problem:
I want to setup Linux in our University's LAN but ran into problems,
because the LAN is VINES-IP based so that normal TCP/IP packet drivers
won't work. The admin says I do need a driver which can tunnel the
normal Linux TCP/IP packets into those VINES-IP packets, so that they
can be send over the LAN to that box which has Internet connection....
Maybe you know if such thing is available and/or where I can get it.
Or maybe you can give some Email-addresses for asking people which
real knowledge 'bout Linux (maybe even that of Linus T. himself) and
it's drivers.
Hope you can help me 8-))
Thanks in advantage
Stefan 8-))
(I've sent your problem on to Linux Journal's Technical Support
column and will post it in Linux Gazette's Mailbag next month.
Neither one will give you a fast answer.
I did a search of LG, LJ and SSC's Linux Resources using VINES as
the keyword. I found only one entry from an author's biography.
It's old -- March 1995 -- and the guy was in the marine corp then
so may or may not be a good address. Anyway here's what it said:
"Jon Frievald ... manages Wide Area Network running Banyan VINES.
... e-mail to jaf@jaflrn.liii.com"
Anyway you might give him a try for help ideas.
For faster access to LG have you tried any of LG's mirror sites in
Germany:
* http://www.cs.uni-dusseldorf.de/~stein/lg
* http://vina12.va.htw-dresden.de/lg
* http://www.fokus.gmd.de/linux/lg
Please note that mirror sites wont help search time -- all
searching is done on SSC site. --Editor)
_________________________________________________________________
GENERAL MAIL
_________________________________________________________________
Date: Sat, 30 Nov 1996 20:35:17 -0600 (CST)
Subject: Re: Slang Applications for Linux
From: Duncan Hill, dhill@sunbeach.net
To: Larry Ayers, layers@vax2.rain.gen.mo.us
On Sat, 30 Nov 1996, Duncan Hill wrote:
Greetings. I was reading your article in the Linux Gazette, and
thought you might be interested to know that Lynx also has its own web
site now at:
http://lynx.browser.org/
It's up to version 2.6 now, and is rather nice, specially with slang
included :)
Duncan Hill, Student of the Barbados Community College
(Thanks for the tip! I really appreciate responses from readers;
confirms that there are really readers out there! --Larry Ayers)
_________________________________________________________________
Date: Sat, 30 Nov 96 16:42:58 0200
Subject: Linux Gazette
From: Paul Beard, paulb@id.co.zw
Hello from Zimbabwe.
Very nice production. Keep up the good work.
Regards,
Paul Beard.
(Thanks. --Editor)
_________________________________________________________________
Date: Thu, 28 Nov 1996 23:54:38 +0000
Subject: Thanks!
From: Russ Spooner, russ1@rmplc.co.uk
Organization: Kontagx
Hi,
I have been an avid reader of Linux Gazette since its inception! I
would just like to say that it has helped me a lot and that I am
really glad that it has become more regular :-)
The Image you have developed now has come a long way and it is now one
of the best organized sites I visit!
Also I would like to thank you for the link to my site :-) it was a
real surprise to "see myself up in lights" :)
Best regards!
Russ Spooner, http://www.pssltd.co.uk/kontagx
_________________________________________________________________
Date: Thu, 28 Nov 1996 12:49:12 -0500
Subject: LG Width
From: frank haynes, frank@vatmom.com
Organization: The Vatmom Organization
Re: LG page width complaint, LG looks great here, and I don't think my
window is particularly large. Keep up the fine work.
--Frank, http://www.mindspring.com/~fmh
(Good to hear. --Editor)
_________________________________________________________________
Date: Fri, 29 Nov 1996 10:30:32 +0000
Subject: LG #12
From: Adam D. Moss. adam@uunet.pipex.com
Nice job on the Gazette, as usual. :)
Adam D. Moss / Consulting
( :-) --Editor)
_________________________________________________________________
Date: Tue, 3 Dec 1996 12:55:18 -0800 (PST)
Subject: Re: images in tcsh article
From: Scott Call, scall@ccnet.com
Most of the images in the TCSH article in issue 12 are broken
-Scott
(You must be looking at one of the mirror sites. I inadvertently
left those images out of the issue12 tar file that I made for the
mirror sites. When I discovered it yesterday, I made an update file
for the mirrors. Unfortunately, I have found that not all the
mirrors are willing to update LG more than once a month, so my
mistakes remain until the next month. Sorry for the inconvenience
and thanks for writing. --Editor)
_________________________________________________________________
Date: Fri, 06 Dec 1996 21:21:00 +0600
Subject: 12? why can you make so bad distributive?????????????
From: Sergey A. Panskih, serg@cnti.chel.su
i ftpgeted lg12 and untar.gz it as made with lg11. lg11 was read as
is: with graphics and so, but lg12... all graphics was loosed. i've
verified hrefs and found out that href was written with principial
errors : i must copy all it to /images in my httpd server!!!!
this a pre-alpha version!!!
i can't do so unfixed products!!!
i'm sorry, but you forgotten how make a http-ready distrbutions... :)
Sergey Panskih
P.S. email me if i'm not true.
(I'm having a little trouble with your English and don't quite
understand what "all graphics was loosed" means. You shouldn't have
to copy anything anywhere: what are you copying to /images?
There is one problem I had that may apply to you. Are you throwing
away previous issues and only getting the current one? If so, I
apologize most humbly. I was not aware until this month that people
were doing this and when I made the tar file I included only new
files and those that had been changed since the last month. To
correct this problem I put a new tar file on the ftp site called
standard_gifs.html. It's not that I've forgotten how to make
http-ready distributions, it's that I'm just learning all the
complexities. In the future I will make the tar file to include all
files needed for the current single issue, whether they were
changed or not.
I am very sorry to have caused you such problems and distress.
--Editor)
_________________________________________________________________
Date: Mon, 02 Dec 96 18:13:48
Subject: spiral trashes letters
From: jep@jephill.com
It's clever and pretty, but the spiral notebook graphic still trashes
the left edge of letters printed in the issue 12 Mailbag.
Problem occurs using OS/2's Web Explorer version 1.2 (comes with OS/2
Warp 4.0). Problem does NOT occur using Netscape 2.02 for OS/2 beta 2
(the latest beta for OS/2).
Problem occurs even while accessing www.ssc.com/lg
Jep Hill
(Problem will always occur with versions of either Microsoft
Explorer or Netscape before 2.0. It is caused by a bug in TABLES
that was fixed in the 2.0 versions. I don't have access to OS/2's
Web Explorer, so I can only guess that it's the same problem. I'd
recommend always using the latest version of your browser.
--Editor)
_________________________________________________________________
Date Mon, 9 Dec 1996 10:14:04 -0800 PST
Subject: Background
From: rayvd@shocking.com
I run at a resolution of 1152x846 (a bit odd I suppose) and although
the Gazette pages look very nice indeed, it is a bit hard to read when
I have my Netscape window maximized. The bindings part of the
background seems to be optimized for a width of 1024 and thus tiles
over again on the right side of the page. This makes reading a bit
difficult as some of the text now overlaps the bindings on the far
right.
I'm not sure if that's a great description of the problem, but I can
easily make you a screenshot if you want to see what I mean.
Anyhow, this is only a minor annoyance--certainly one I'm willing to
live with in order to read your great 'zine. :)
Ray Van Dolson -=-=- Bludgeon Creations (Web Design) - DALnet
#Bludgeon -- http://www.shocking.com/~rayvd/
(Screen shot wont be necessary. When the web master first put the
spiral out there, the same thing happened to me -- I use a large
window too, but not as large as yours. He was able to expand it to
fix it at that time. I notified him of your problem, but not sure
if he can expand it even more or not. We'll see. Glad it's a
problem you can live with. :-) --Editor)
_________________________________________________________________
Date: Sat, 7 Dec 1996 22:16:55 +0100 (MET)
Subject: Problem with Printing.
From: fm@M1.whitespace.de
Hi,
This is just to let you people know, that there might be a slight
problem. I want to point out and make it perfectly clear that this is
NOT a complaint. I feel perfectly satisfied with the Linux Gazette as
it is.
However sometimes I prefer to have a printed copy to take with me.
Therefore I used to print the LG. from Netscape. I'm using the new 3.1
version now. With the last two issues I have difficulties doing so.
All the pages with this new nice look don't print too well. The
graphics show up at all the wrong places and only one page is printed
on the paper. The rest is swallowed. Did you ever try to print it?
I had to use an ancient copy of Mosaic, that doesn't know anything
about tables, to print these pages. They don't look too good this way
too, and never did. I know this old Mosaic is buggy. At least it
doesn't swallow half of the stuff. This could as well be a bug in
Netscape. I know next to nothing about html.
Anyway, have fun.
Regards Friedhelm
(No, I don't try to print it, but will look into it. Are you
printing out "TWDT" from the TOC or trying to do it
page by page? It is out there in multi-file format and so if you
print from say the Front Page, the front page is all you'll get.
"TWDT" is one single file containing the whole
issue, and the spiral and table stuff are removed so it should
print out for you okay. Let me know if this is already what you are
printing, so I'll know where to look for the problem. --Editor)
_________________________________________________________________
Date: Wed, 18 Dec 1996 04:02:37 +0200
Subject: Greetings
From: Trucza Csaba, ctrucza@cemc.soroscj.roi
To: fiskjm@ctrvax.Vanderbilt.Edu
Well, Hi there!
Amazing. I've just read the Linux Gazette from the first issue to this
one, the 12th (actually I read just the first 7 issues through,
because the others were not downloaded correctly).
It's 4 in the morning and I'm enthusiastic. I knew Linux was good, I'm
using it for a year (this is because of the lack of my english
grammar, I mean the previous sentence, well...), so I knew it was
good, but I didn't expect to see something so nice like this Gazette.
It's good to see that there are a WHOLE LOT of people with huge will
to share.
I think we owe You a lot of thanks for starting it.
Merry Christmas, a Happy New Year, and keep it up!
Trucza Csaba, Romania
(Thanks, I will. -- Editor)
_________________________________________________________________
Date: Mon, 23 Dec 1996 12:16:30 -0800 (PST)
Subject: lg issue 12 via ftp?
From: schwarz@monet.m.isar.de (Christian Schwarz)
I just saw that issue #12 is out and accessible via WWW, but I can't
find the file on your ftp server nor on any mirrors.
(Sorry for the problems. We changed web servers and I went on
vacation. Somehow in the web server change, some of the December
files got left behind. I didn't realize until today that this had
happened. Sorry for the inconvenience. --Editor)
_________________________________________________________________
Date: Fri, 20 Dec 1996 00:31:45 -0500
Subject: Great IDEA
From: Pedro A Cruz, pcruz@panixc.com
Hi:
I visited your site recently and was astounded by the wealth of
information there. I have lots of bandwidth to read your site. I
noticed that you have issues for download. I Think it will be a great
service to the LINUX community if you consider publishing a CDROM
(maybe from walnut creek cdrom) as a subscription item.
pedro
(Yes, that is a good idea. I'll talk to my publisher about it.
--Editor)
_________________________________________________________________
Date: Sun, 22 Dec 1996 20:24:51 -0600
Subject: Linux as router
From: Robert Binz, rbinz@swconnect.net
I have found myself trying to learn how to use Linux as a usenet
server to provide news feeds to people, and to use Linux as a IRC
server. Information on these topics are hard to come buy. If you have
any sources on these subjects that you can point me to I would be most
appreciative.
But any how, I have found an article in SysAdmin (Jan 96 (5.1)) that
is titled Using Linux as a Router, by johnathon Feldman. Is it
possible to reprint this article or get the author to write a new one
for you?
TIA
Robert Binz
(I'll look into it. In the meantime, I've forwarded your letter to a
guy I think may be able to help you. --Editor)
_________________________________________________________________
Date: Fri, 13 Dec 1996 03:57:09 -0500 (EST)
Subject: Correction for LG #12
From: Joe Hohertz, jhohertz@golden.net
Organization: Golden Triangle On-Line
Noticed the folowing in the News section.
A couple of new Linux Resources sites:
(Seems I had Joe's address wrong. Sorry. --Editor)
_________________________________________________________________
Date: Tue, 17 Dec 1996 01:19:43 -0500
Subject: One-shot downloads
From: David M. Razler, david.razler@postoffice.worldnet.att.net
Folks:
While I realize that the economies of the LINUX biz require that there
be some method of making money even on the distribution of free and
"free" software, I have a request for them of us who 1) are currently
scraping for the cash for our Internet accounts and 2) would like to
try LINUX.
How about a one-shot download? I mean, oh, everything needed to
establish a LINUX system in one ZIP'ed (or tar/gz'd, though zip is a
more compatible format) file, one for each distribution?
I'm currently looking to establish LINUX on my "spare" PC, a 386DX-16
w/4 meg and a scavenged 2500MB IDE drive, etc. It will be relatively
slow, limited, lacks a CD-rom drive, but it's free, since the machine
is currently serving as a paperweight.
I could go out and buy a used CD-rom for the beast, or run a bastard
connection from my primary, indispensable work machine and buy the
CDs. But I am currently disabled and spending for these things has to
be weighed against other expenses (admittedly, I am certainly lucky
and not destitute, it would just be better)
I could get a web robot and download umpteen little files, puzzle them
out and put them together, though the load on your server would be
higher.
Or, under my proposed system, I could download Distribution Code,
Documents, and Major accessories in one group, then go back for the
individual bits and pieces I need to build my system.
Again, I realize that running your site costs money, and that people
make money, admirably little money, distributing LINUX on CDs, with
the big bucks (grin) of LINUX coming in non-free software, support and
book sales.
But if the system is to spread, providing a series of one-shot
downloads, possibly available only to individuals (I believe one could
copyright the *package* and require someone downloading to agree to
use it only on a single non-commercial system and not to redistribute,
but I am not an intellectual properties lawyer), to make life easier
for them of us who need to learn a UNIX-style system and build one on
the cheap.
dmr
_________________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Next
This page written and maintained by the Editor of Linux Gazette,
gazette@ssc.com
Copyright © 1997 Specialized Systems Consultants, Inc.
"Linux Gazette...making Linux just a little more fun! "
_________________________________________________________________
MORE 2<> TIPS!
Send Linux Tips and Tricks to gazette@ssc.com
_________________________________________________________________
CONTENTS:
* Another 2cent Tip for LG
* Console Trick Follow-up
* GIF Animations
* How to close and reopen a new /var/adm/messages file
* How to truncate /var/adm/messages
* Info-ZIP encryption code
* Kernel Compile Woes
* Letter 1 to LJ Editor re Titlebar
* Letter 2 to LJ Editor re Titlebar
* PPP redialer script--A Quick Hack
* TABLE tags in HTML
* Text File undelete
* Truncating /var/adm/messages
* 2c Host Trick
* Use of TCSH's :e and :r Extensions
* Various notes on 2c tips, Gazette 12
* Viewing HOWTO Documents
* Xaw-XPM .Xresources troubleshooting tip
* Xterm Titlebar
_________________________________________________________________
ANOTHER 2CENT SCRIPT FOR LG
Date: Wed, 11 Dec 1996 23:34:58 +0100
From: Hans Zoebelein, zocki@goldfish.cube.net
Hello LG people,
here comes a short script which will check from time to time that
there is enough free space available on anything which shows up in
mount (disks, cdrom, floppy...)
If space runs out, a message is printed every X seconds to the screen
and 1 mail message per filled device is fired up.
Enjoy!
Hans
#!/bin/sh
#
# $Id: issue13.txt,v 1.1.1.1 2002/08/14 22:26:57 dan Exp $
#
#
# Since I got mysterious error messages during compile when
# tmp files filled up my disks, I wrote this to get a warning
# before disks are full.
#
# If this stuff saved your servers from exploding,
# send praising email to zocki@goldfish.cube.net.
# If your site burns down because of this, sorry but I
# warned you: no comps.
# If you really know how to handle sed, please forgive me :)
#
#
# Shoot and forget: Put 'check_hdspace &' in rc.local.
# Checks for free space on devices every $SLEEPTIME sec.
# You even might check your floppies or tape drives. :)
# If free space is below $MINFREE (kb), it will echo a warning
# and send one mail for each triggering device to $MAIL_TO_ME.
# If there is more free space than trigger limit again,
# mail action is also armed again.
#
# TODO: Different $MINFREE for each device.
# Free /*tmp dirs securely from old junk stuff if no more free space.
DEVICES='/dev/sda2 /dev/sda8 /dev/sda9' # device; your put disks here
MINFREE=20480 # kb; below this do warning
SLEEPTIME=10 # sec; sleep between checks
MAIL_TO_ME='root@localhost' # fool; to whom mail warning
# ------- no changes needed below this line (hopefully :) -------
MINMB=0
ISFREE=0
MAILED=""
let MINMB=$MINFREE/1024 # yep, we are strict :)
while [ 1 ]; do
DF="`/bin/df`"
for DEVICE in $DEVICES ; do
ISFREE=`echo $DF | sed s#.\*$DEVICE" "\*[0-9]\*" "\*[0-9]\*" "\
*## | sed s#" ".\*##`
if [ $ISFREE -le $MINFREE ] ; then
let ISMB=$ISFREE/1024
echo "WARNING: $DEVICE only $ISMB mb free." >&2
#echo "more stuff here" >&2
echo -e "\a\a\a\a"
if [ -z "`echo $MAILED | grep -w $DEVICE`" ] ; then
echo "WARNING: $DEVICE only $ISMB mb free.
(Trigger is set to $MINMB mb)" \
| mail -s "WARNING: $DEVICE only $ISMB mb free!
" $MAIL_TO_ME
MAILEDH="$MAILED $DEVICE"
MAILED=$MAILEDH
# put further action here like cleaning
# up */tmp dirs...
fi
elif [ -n "`echo $MAILED | grep -w $DEVICE`" ] ; then
# Remove mailed marker if enough disk space
# again. So we are ready for new mailing action.
MAILEDH="`echo $MAILED | sed s#$DEVICE##`"
MAILED=$MAILEDH
fi
done
sleep $SLEEPTIME
done
_________________________________________________________________
CONSOLE TRICK FOLLOW-UP
Date: Wed, 27 Nov 1996 16:20:06 -0500 (EST)
From: Elliot Lee, sopwith@cuc.edu
Just finished reading issue #12, nice work.
A followup to the "Console Tricks" 2-cent tip:
What I like to do is have a line in /etc/syslog.conf that says:
*.* /dev/tty10
that sends all messages to VC 10, so I can know what's going on
whether in X or text mode. Very useful IMHO.
-- Elliot, http://www.redhat.com/
_________________________________________________________________
GIF ANIMATIONS
Date: Thu, 28 Nov 1996 20:41:22 -0600 (CST)
From: Greg Roelofs, newt@pobox.com
I too thought WhirlGIF (Graphics Muse, issue 12) was the greatest
thing since sliced bread (well, aside from PNG) when I first
discovered it, but for creating animations, it's considerably inferior
to Andy Wardley's MultiGIF. The latter can specify tiny sprite images
as parts of the animation, not just full images. For my PNG-balls
animation (see http://quest.jpl.nasa.gov/PNG/), this resulted in well
over a factor-of-two reduction in size (577k to 233k). For another
animation with a small, horizontally oscillating (Cylon eyes) sprite,
the savings was more than a factor of 20(!).
MultiGIF is available as source code, of course. (And I had nothing to
do with it, but I do find it darned handy.)
Regards,
Greg Roelofs, http://pobox.com/~newt/
Newtware, Info-ZIP, PNG Group, U Chicago, Philips Research, ...
_________________________________________________________________
RE: HOW TO CLOSE AND REOPEN A NEW /VAR/ADM/MESSAGES FILE
Date: Thu, 05 Dec 1996 01:09:27 -0800
From: CyberTech, CyberTech@ns.cybertech.org
Regarding the posting in issue #12 of your gazette, how to backup the
current messages file & recreate, here is an alternative method...
Place the lines at the end of this messages in a shell script
(/root/cron/swaplogs in this example). Don't forget to make it +x!
Execute it with 'sh scriptname', or by adding the following lines to
your (root's) crontab:
# Swap logfiles every day at 1 am, local time
0 01 * * * /root/cron/swaplogs
The advantage to this method over renaming the logfile and creating a
new one is that in this method, syslogd is not required to be
restarted.
#!/bin/sh
cp /var/adm/messages /var/adm/messages.`date +%d-%m-%y_%T`
cat /dev/null >/var/adm/messages
cp /var/adm/syslog /var/adm/syslog.`date +%d-%m-%y_%T`
cat /dev/null >/var/adm/syslog
cp /var/adm/debug /var/adm/debug.`date +%d-%m-%y_%T`
cat /dev/null >/var/adm/debug
_________________________________________________________________
HOW TO TRUNCATE /VAR/ADM/MESSAGES
Date: Mon, 02 Dec 1996 16:47:20 +0100
From: Eje Gustafsson, gne@ffa.se
>In answer to the question:
>
> What is the proper way to close and reopen a new >/var/adm/message
s
> file from a running system?
>
> Step one: rename the file. Syslog will still be writing in it >after re
naming so you don't
> lose messages. Step two: create a new one. After re-initializing >syslo
gd it will be used.
>just re-initialize.
>
> 1.mv /var/adm/messages /var/adm/messages.prev
> 2.touch /var/adm/messages
> 3.kill -1 pid-of-syslogd
>
> This should work on a decent Unix(like) system, and I know Linux >is on
e of them.
This is NOT an proper way of truncate /var/adm/messages.
It is better to do:
1. cp /var/adm/messages /var/adm/messages.prev
2. >/var/adm/messages or cp /dev/null /var/adm/messages (both of them
makes the file empty).
3. No more.
The problem is that when you remove the /var/adm/messages syslogd gets
confused and unhappy and you have to give syslogd a HUPSIG but if you
just sets the file length to zero without removing the file syslogd
don't complain. And if you are really unlucky your system will go down
because you didn't create /var/adm/messages quick enough or forgot it.
Best of regards,
Eje Gustafsson, System Administrator
THE AERONAUTICAL RESEARCH INSTITUTE OF SWEDEN
_________________________________________________________________
INFO-ZIP ENCRYPTION CODE
Date: Thu, 28 Nov 1996 20:58:39 -0600 (CST)
From: Greg Roelofs, newt@pobox.com
This is a relatively minor point, but Info-ZIP's Zip/UnZip encryption
code is *not* DES as reported in Robert Savage's article (LG issue
12). It's actually considerably weaker, so much so that Paul Kocher
has pub- lished a known-plaintext attack (the existence of which is
undoubtedly the reason PKWARE was granted an export license for the
code). While the encryption is good enough to keep your mom and
probably your boss from reading your files, those who desire *real*
security should look to PGP (which is also based on Info-ZIP code, but
only for compression).
And while I'm at it, Linux users will be happy to learn that the
upcoming releases of UnZip 5.3 and Zip 2.2 will be noticeably faster
than the cur- rent publicly released code. In Zip's case this is due
to a work-around for a gcc bug that prevented a key assembler routine
from being used--Zip is now 30-40% faster on large files. In UnZip's
case the improvement is due to a couple of things, one of which is
simply better-optimized CRC code. UnZip 5.3 is about 10-20% faster
than 5.2, I believe. The new ver- sions should be released in early
January, if all goes well. And then... we start working on multi-part
archives. :-)
Greg Roelofs, http://pobox.com/~newt/
Newtware, Info-ZIP, PNG Group, U Chicago, Philips Research, ...
_________________________________________________________________
KERNEL COMPILE WOES
Date: Mon, 2 Dec 1996 21:35:29 +0400 (GMT-4)
From: Duncan Hill, dhill@sunbeach.net
Greetings. Having been through hell after a recompile of my kernel, I
thought I'd pass this on.
It all started with me compiling a kernel for JAVA binary support..who
tell me do that. Somehow I think I got experimental code in..even
worse :> Anyway, it resulted in a crash, and I couldn't recompile
since then.
Well, after several cries for help, and trying all sorts of stuff, I
upgraded binutils to 2.7.0.3, and told the kernel to build elf support
and in elf format, and hey presto. I'd been wrestling with the problem
for well over a week, and every time, I'd get an error. Unfortunately,
I had to take out sound support, so I'm going to see if it'll add back
in.
I have to say thank you to the folks on the linux-kernel mailing list
at vger.rutgers.edu. I posted there once, and had back at least 5
replies in an hour. (One came back in 10 minutes).
As for the LG, it looks very nice seen thru Lynx 2-6 (no graphics to
get messed up :>) I love the Weekend Mechanic, and the 2 cent tips
mainly. Perhaps one day I'll contribute something,.
Duncan Hill, Student of the Barbados Community College
http://www.sunbeach.net/personal/dhill/dhill.htm
http://www.sunbeach.net/personal/dhill/lynx/lynx-main.html
_________________________________________________________________
LETTER 1 TO THE LJ EDITOR RE TITLEBAR
Date: Sat, 21 Dec 1996 15:18:01 -0600
From: Roger Booth, Roger_Booth@crow.bmc.com
To: linux@ssc.com The Jan97 Issue 33 of Linux Journal contained the
"Linux Gazette Two Cent Tips". I was interested in the tip "X Term
Titlebar Function". Although the text of the tip stated that the tip
would work in ksh-based systems, I could not get it to work as shown.
I think there are three problems. First, I think there are a few
transcription errors in the script. Second, I believe the author is
using embedded control characters and it was not obvious to me which
character sequences are representations of control characters and
which characters should be typed verbatim. Third, the author uses a
command-line option to the echo command which is not available on all
Unix platforms.
I finally used the following script:
if [ ${SHELL##/*/} = "ksh" ] ; then
if [[ $TERM = x"term" ]] ; then
HOSTNAME=`uname -n`
label () { echo "\\033]2;$*\\007\\c"; }
alias stripe='label $LOGNAME on $HOSTNAME - ${PWD#$HOME/}'
cds () { "cd" $*; eval stripe; }
alias cd=cds
eval stripe
fi
fi
I don't use vi, so I left out that functionality.
The functional changes I made are all in the arguments to the echo
command. The changes are to use \\033 rather than what was shown in
the original tip as ^[, to use \\007 rather than ^G, and to terminate
the string with \\c rather than use the option -n.
On AIX 4.1, the command "echo -n hi" echoes "-n hi"; in other words,
-n is not a portable command-line option to the echo command. I tested
the above script on AIX 3.2, AIX 4.1, HPUX 9.0, HPUX 10.0, Solaris 2.4
and Solaris 2.5. I'm still trying to get Linux and my Wintel box
mutually configured, so I haven't tested it on Linux.
I have noticed a problem with this script. I use the rlogin command to
log in to a remote box. When I exit from the remote box, the caption
is not updated, and still shows the hostname and path that was valid
just before I exited. I tried adding
exits () { "exit" $*; eval stripe; }
alias exit=exits
and
rlogins () { "rlogin" $*; eval stripe; }
alias rlogin=rlogins
Neither addition updated the caption to the host/path returned to. Any
suggestions?
Roger Booth, rbooth@bmc.com
_________________________________________________________________
LETTER 2 TO THE LJ EDITOR RE TITLEBAR
Date: Fri, 13 Dec 1996 23:03:37 -0700 (MST) From: Gary Masters,
gmasters@csn.net
Some further clarification is needed with respect to the X Term
Titlebar Function tip in the Linux Gazette Two Cent Tips column of the
January 1997 issue. With regard to the -print option to find, Michael
Hammel says, "Linux does require this." This is yet another example of
"Your mileage may vary." Some versions of Linux do not require the
-print option. And, although Solaris may not, SunOS 4.1.3_U1 and 4.1.4
do require the -print option. Also, if running csh or tcsh, remember
to escape wildcards in the file specification ( e.g. find ./ -name
\*txt\* ) so that the shell doesn't attempt to expand them.
Second, for those tcsh fans out there, here is an xterm title bar
function for tcsh.
NOTE: This works on Slackware 3.0 with tcsh version 6.04.00, under the
tab, fv, and OpenLook window managers. Your mileage may vary.
if ( $TERM == xterm ) then
set prompt="%h> "
alias cwdcmd 'echo -n "^[]2;`whoami` on ${HOST} - $cwd^G^[]1;${HOST}^G"'
alias vi 'echo -n "^[]2;${HOST} - editing file-> \!*^G" ; vim \!* ;
cwdcmd'
alias telnet '/bin/telnet \!* ; cwdcmd'
alias rlogin '/usr/bin/rlogin \!* ; cwdcmd'
cwdcmd
else
set prompt="[%m]%~% "
endif
1. Check to see if tcsh is running in an xterm.
2. Set the prompt to show the current history event number.
3. Set the alias cwdcmd to display the user, host, and current path
in the xterm title bar, and set the icon name to the host name.
cwdcmd is a special tcsh alias, which if set holds a command that
will be executed after changing the value of $cwd.
4. Set a vi alias to display the user, host, and file name under edit
in the xterm title bar. And run cwdcmd on exit to restore the
xterm title bar and icon name.
5. Alias telnet and rlogin to restore the xterm title bar and icon
name upon exit. NOTE: Paths to telnet and rlogin may vary.
6. Run the alias cwdcmd to set the initial xterm title bar and icon
name.
7. If this wasn't an xterm, set the prompt to show hostname and path.
Gary Masters
_____________________________________________________________
PPP REDIALER SCRIPT--A QUICK HACK
Date: Sun, 08 Dec 1996 13:20:25 +0200
From: Markku J. Salama, msalama@usa.net
This here is the way I do it, but don't use it if your area has
some regulations about redialing the same phone numbers over and
over:
#!/bin/sh
# A quick hack for redialing with ppp by
# Tries 2 numbers sequentially until connected
# Takes 1 cmdline parm, the interface (ppp0, ppp1...)
# You need 2 copies of the ppp-on script (here called modemon{1,2}) with
# different telephone numbers for the ISP. These scripts should be
slightly
# customized so that the passwd is _not_ written in them, but is taken
# separately from the user in the main (a.k.a. this) script.
# Here's how (from the customized ppp-on a.k.a. modemon1):
# ...
# TELEPHONE=your.isp.number1 # Then make a copy of this script ->
modemon2
# and change this to your.isp.number2
# ACCOUNT=your.account
# PASSWD=$1 # This gets the passwd from the main
script.
# ...
# /sbin/ifconfig must be user-executable for this hack to work.
wd1=1 # counter start
stty -echo # echo off
echo -n "Password: " # for the ISP
account
read wd2
stty echo # back on
echo
echo "Trying..."
echo 'ATE V1 M0 &K3 &C1 ^M' > /dev/modem # modem init,
# change as
needed
/usr/sbin/modemon1 $wd2 # first try
flag=1 # locked
while [ 1 ]; do # just keep on
going
if [ "$flag" = 1 ]; then # locked?
bar=$(ifconfig | grep -c $1) # check for a link
if [ "$bar" = 1 ]; then # connected?
echo "Connected!" # if so, then
exit 0 # get outta here
else
foo=$(ps ax) # already
running?
blaat=$(echo $foo | grep "/usr/sbin/pppd")
if [ "$blaat" = "" ]; then # if not, then
flag=0 # unset lock
fi
fi
else # no lock, ready
# to continue
wd1=$[wd1+1]
echo "Trying again... $wd1"
if [ $[wd1%2] = 1 ]; then # this modulo
test
/usr/sbin/modemon1 $wd2 # does the
switching
else # between the 2
numbers
/usr/sbin/modemon2 $wd2 # we are using
fi
flag=1 # locked again
fi
done # All done!
There. Customize as needed & be an excellent person. Ant DON'T break
any laws if redialing is illegal in your area!
Mark
_____________________________________________________________
TABLE TAGS IN HTML
Date: Fri, 20 Dec 1996 11:51:22 -0500
From: Michael O'Keefe, Michael.OKeefe@LMC.Ericsson.SE
Organization: Ericsson Research Canada
G'day,
Just browsing through the mailbox, and I noticed your reply to a
user about HTML standard compliance and long download times. You
replied that you use the spiral image (a common thing these days)
inside a <TABLE>.
I hope you are aware that a browser cannot display any contents of
a <TABLE> until it has received the </TABLE> tag (no matter what
version of any browser - it is a limitation of the HTML tag)
because the browser cannot run its algorithm until it has received
all of the <TR> and <TD> tags, and it can't be sure of that until
the </TABLE> tag comes through. I have seen many complex sites,
using many images (thankfully they at least used the HEIGHT and
WIDTH tags on those images to tell the browser how big the image
will be so it didn't have to download it to find out) but still,
putting it in a table nullifies much of the speediness that users
require.
A solution I often offer the HTML designers under me is to use a
<DL><DD> combination. Though this doesn't technically fit the HTML
DTD (certain elements are not allowed in a <DL>) and I use an
editor that will not allow illegal HTML, so I can't do it myself
(without going via a backdoor - but that's bad quality in my
opionion). The downside of the this is of course that you don't
know what sized FONT the user has set on the browser, and the FONT
size affects the indetation width of the <DD> element. But if your
spiral image is not too wide, then that could be made a NULL
factor. The plus to the <DL><DD> is that the page can be displayed
instantly as it comes down (again..providing the developer uses
the HEIGHT and WIDTH attributes on *ALL* images so that the
browser doesn't have to pause it's display to get the image and
work out how to lay out around the image)
Michael O'Keefe
_____________________________________________________________
TEXT FILE UNDELETE
Date: Sat, 7 Dec 1996 15:00:58 +1300 (NZDT)
From: Michael Hamilton, michael@actrix.gen.nz
Here's a trick I've had to use a few times.
Desperate person's text file undelete.
If you accidentally remove a text file, for example, some email,
or the results of a late night programming session, all may not be
lost. If the file ever made it to disk, ie it was around for more
than 30 seconds, its contents may still be in the disk partition.
You can use the grep command to search the raw disk partition for
the contents of file.
For example, recently, I accidentally deleted a piece of email. So
I immediately ceased any activity that could modify that
partition: in this case I just refrained from saving any files or
doing any compiles etc. On other occasions, I've actually gone to
the trouble of bring the system down to single user mode, and
unmounted the filesystem.
I then used the egrep command on the disk partition: in my case
the email message was in /usr/local/home/michael/, so from the
output from df, I could see this was in /dev/hdb5
sputnik3:~ % df
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/hda3 18621 9759 7901 55% /
/dev/hdb3 308852 258443 34458 88% /usr
/dev/hdb5 466896 407062 35720 92% /usr/local
sputnik3:~ % su
Password:
[michael@sputnik3 michael]# egrep -50 'ftp.+COL' /dev/hdb5 > /tmp/x
Now I'm ultra careful when fooling around with disk partitions, so I
paused to make sure I understood the command syntax BEFORE
pressing return. In this case the email contained the word 'ftp'
followed by some text followed by the word 'COL'. The message was
about 20 lines long, so I used -50 to get all the lines around the
phrase. In the past I've used -3000 to make sure I got all the
lines of some source code. I directed the output from the egrep to
a different disk partition - this prevented it from over writing
the message I was looking for.
I then used strings to help me inspect the output
strings /tmp/x | less
Sure enough the email was in there.
This method can't be relied on, all, or some, of the disk space
may have already been re-used.
This trick is probably only useful on single user systems. On
multi-users systems with high disk activity, the space you free'ed
up may have already been reused. And most of use can't just rip
the box out from under our users when ever we need to recover a
file.
On my home system this trick has come in handy on about three
occasions in the past few years - usually when I accidentally
trash some of the days work. If what I'm working survives to a
point where I feel I made significant progress, it get's backed up
onto floppy, so I haven't needed this trick very often.
Michael
_____________________________________________________________
TRUNCATING /VAR/ADM/MESSAGES
Date: Tue, 31 Dec 1996 15:32:57 GMT+100
From: Michel Vanaken, michel@idtech.be
Organization: IDtech
Hi !
About the topic "How to truncate /var/adm/messages", here's the
way to do it with a shell script :
mv /var/adm/messages /var/adm/messages.prev
touch /var/adm/messages
mv /var/adm/syslog /var/adm/syslog.prev
touch /var/adm/syslog
kill -1 `ps x | grep syslog | grep -v grep | awk '{ print $1 }'`
Happy new year !
Michel
_____________________________________________________________
2C HOST TRICK
Date: Tue, 10 Dec 1996 17:27:46 +0300
From: Paul Makeev, mac@rosprint.ru
In order to make DHCPD by ISC/Vixie to run under Linux, you should
have route to host 255.255.255.255. Standard "route" from
Slackware distribution does not like the string "route add -host
255.255.255.255 dev eth0". But you can add hostname to your
/etc/hosts file with address 255.255.255.255, and use "route add
hostname dev eth0" instead. It works.
Paul.
_____________________________________________________________
USE OF TCSH'S :E AND :R EXTENSIONS
Date: Mon, 02 Dec 1996 23:25:23 -0500
From: Bill C. Riemers, bcr@feynman.com
I'd like to congratulate Jesper Pedersen on his article on tcsh
tricks. Tcsh has long been my favorite shell. But most of the
features Jesper hit upon are also found in bash. Tcsh's most
useful and unique features are its variable/history suffixes.
For example, if after applying a patch one wishes to undo things,
by moving the *.orig files to there base names, the :r extension
which means to strip the extension comes in handy. e.g.
foreach a ( *.orig )
mv $a $a:r
end
The same loop for ksh looks like:
for a in *.orig; do=20
mv $a `echo $a|sed -e 's,\.orig$,,g'`
done
Even better, one can use the :e extension to extract the file
extension. For example, lets say we we want to do the same thing
on compressed files:
foreach a ( *.orig.{gz,Z} )
mv $a $a:r:r.$a:e
end
The $a:r:r is the filename without .orig.gz and .orig.Z, we tack the
.gz or .Z back on with .$a:e.
Bill
_____________________________________________________________
VARIOUS NOTES ON 2C TIPS, GAZETTE 12
Date: Wed, 04 Dec 1996 15:30:21 -0600
From: Justin Dossey, dossey@ou.edu
I noticed a few overly difficult or unnecessary procedures
recommended in the 2c tips section of Issue 12. Since there is
more than one, I'm sending it to you:
#!/bin/sh
# lowerit
# convert all file names in the current directory to lower case
# only operates on plain files--does not change the name of
directories
# will ask for verification before overwriting an existing file
for x in `ls`
do
if [ ! -f $x ]; then
continue
fi
lc=`echo $x | tr '[A-Z]' '[a-z]'`
if [ $lc != $x ]; then
mv -i $x $lc
fi
done
Wow. That's a long script. I wouldn't write a script to do that;
instead, I would use this command:
for i in * ; do [ -f $i ] && mv -i $i `echo $i | tr '[A-Z]' '[a-z]'`;
done;
on the command line.
The contributor says he wrote the script how he did for
understandability (see below).
On the next tip, this one about adding and removing users, Geoff
is doing fine until that last step. Reboot? Boy, I hope he doesn't
reboot every time he removes a user. All you have to do is the
first two steps. What sort of processes would that user have
going, anyway? An irc bot? Killing the processes with a simple
kill -9 `ps -aux |grep ^ |tr -s " " |cut -d " " -f2`
Example, username is foo
kill -9 `ps -aux |grep ^foo |tr -s " " |cut -d " " -f2`
That taken care of, let us move to the forgotten root password.
The solution given in the Gazette is the most universal one, but
not the easiest one. With both LILO and loadlin, one may provide
the boot parameter "single" to boot directly into the default
shell with no login or password prompt. From there, one may change
or remove any passwords before typing ``init 3``to start multiuser
mode. Number of reboots: 1 The other way Number of reboots: 2
That's just about it. Thanks for the great magazine and continuing
contribution to the Linux community. The Gazette is a needed
element for many linux users on the 'net.
Justin Dossey
Date: Wed, 4 Dec 1996 08:46:24 -0800 (PST)
Subject: Re: lowerit shell script in the LG
From: Phil Hughes, phil@ssc.com
The amazing Justin Dossey wrote:
> #!/bin/sh
> for i in * ; do [ -f $i ] && mv -i $i `echo $i | tr '[A-Z]' '[a-z]'`;
> done;
>
> may be more cryptic than
...
>
> but it is a lot nicer to the system (speed & memory-wise) too.
Can't argue. If I had written it for what I considered a high usage
situation I would have done it more like you suggested. The
intent, however, was to make something that could be easily
understood.
Phil Hughes
_____________________________________________________________
VIEWING HOWTO DOCUMENTS
Date: Sun, 22 Dec 1996 09:43:40 -0800
From: Didier Juges, dj@destin.nfds.net
>From a newbie to another, here is a short script that eases
looking for and viewing howto documents. My howto's are in
/usr/doc/faq/howto/ and are gzipped. The file names are
XXX-HOWTO.gz, XXX being the subject. I created the following
script called "howto" in the /usr/local/sbin directory:
#!/bin/sh
if [ "$1" = "" ]; then
ls /usr/doc/faq/howto | less
else
gunzip -c /usr/doc/faq/howto/$1-HOWTO.gz | less
fi
When called without argument, it displays a directory of the available
howto's. Then when entered with the first part of the file name
(before the hyphen) as an argument, it unzips (keeping the
original intact) then displays the document.
For instance, to view the Serial-HOWTO.gz document, enter: $ howto
Serial
Keep up the good work.
Didier
_____________________________________________________________
XAW-XPM .XRESOURCES TROUBLESHOOTING TIP.
Date: Wed, 18 Dec 1996 17:02:07 +0100 (GMT+0100)
From: Robin Smidsroed, dex@sysedata.no
I'm sure a lot of you folks out there have installed the new
Xaw-XPM and like it a lot. But I've had some trouble with it. If I
don't install the supplied .Xresources-file, xcalc and some other
apps (ghostview is one) segfaults whenever you try to use them.
I found out that the entry which causes this, is this:
*setPixmap: /path/to/an/xpm-file
If this entry isn't in your .Xresources, xcalc and ghostview won't
work. Hope some of you out there need this.
And while you're at ghostview, remember to upgrade ghostscript to
the latest version to get the new and improved fonts, they
certainly look better on paper than the old versions.
Ciao!
Robin
PS: Great mag, now I'm just waiting for the arrival of my copy of
LJ
_____________________________________________________________
XTERM TITLE BAR
Date: Wed, 18 Dec 1996 21:21:47 -0800 (PST) From: bradshaw@nlc.com
(Lee Bradshaw)
Hi Guys,
I noticed the "alias for cd xterm title bar tip" from Michael
Hammel in the Linux Gazette and wanted to offer a possible
improvement for your .bashrc file. A similar solution might work
for ksh, but you may need to substitute $HOSTNAME for \h, etc:
if [ "x$TERM" = "xxterm" ]; then
PS1='\h \w-> \[\033]0;\h \w\007\]'
else
PS1='\h \w-> '
fi
PS1 is an environment variable used in bash and ksh for storing the
normal prompt. \h and \w are shorthand for hostname and working
directory in bash. The \[ and \] strings enclose non-printing
characters from the prompt so that command line editing will work
correctly. The \O33]0; and \007 strings enclose a string which
xterm will use for the title bar and icon name. Sorry, I don't
remember the codes for setting these independently. (ksh users
note: \033 is octal for ESC and \007 is octal for CTRL-G.) This
example just changes the title bar and icon names to match the
prompt before the cursor.
Any program which changes the xterm title will cause
inconsistencies if you try an alias for cd instead of PS1.
Consider rlogin to another machine which changes the xterm title.
When you quit rlogin, there is nothing to force the xterm title
back to the correct value when using the cd alias (at least not
until the next cd). This is not a problem when using PS1.
You could still alias vi to change the xterm title bar, but it may
not always be correct. If you use ":e filename" to edit a new
file, vi will not update the xterm title. I would suggest
upgrading to vim (VI iMproved). It has many nice new features in
addition to displaying the current filename on the xterm title.
Hopefully this tip is a good starting point for some more
experimenting. Good luck!
Lee Bradshaw, bradshaw@nlc.com
_____________________________________________________________
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_____________________________________________________________
This page maintained by the Editor of Linux Gazette, gazette@ssc.com
Copyright &copy; 1997 Specialized Systems Consultants, Inc.
"Linux Gazette...making Linux just a little more fun!"
_____________________________________________________________
News Bytes
CONTENTS:
+ News in General
+ Software Announcements
_____________________________________________________________
NEWS IN GENERAL
_____________________________________________________________
SECURITY: (LINUX-ALERT) LSF UPDATE#14: VULNERABILITY OF THE LPR PROGRAM.
Date: Sat, 26 Nov 1996
Linux Security FAQ Update -- lpr Vulnerability
A vulnerability exists in the lpr program version 0.06. If
installed suid to root, the lpr program allows local users to gain
access to a super-user account.
Local users can gain root privileges. The exploits that exercise
this vulnerability were made available.
lpr utility from the lpr 0.06 suffers from the buffer overrun
problem. Installing lpr as a suid-to-root is needed to allow print
spooling.
This LSF Update is based on the information originally posted to
linux-security mailing list.
For additional information and distribution corrections:
Linux Security WWW:
http://bach.cis.temple.edu/linux/linux-security linux-security &
linux-alert mailing list archives:
ftp://linux.nrao.edu/pub/linux/security/list-archive
_____________________________________________________________
LINUXEXPO '97 TECHNICAL CONFERENCE
Durham, N.C. December 31,1996-- It was announced today that the
third annual LinuxExpo Technical Conference will be held at the
N.C. Biotechnology Center in Research Triangle Park, NC on April
4-5, 1997. The conference will consist of fourteen elite
developers who will give technical talks on various topics all
related to the development of Linux. This year the event is
expected to draw 1,000 attendees who will be coming not only for
the conference, but to visit the estimated 30 Linux companies and
organizations that will be selling their own Linux products and
giving demonstrations. The event will also include a Linux User's
Group meeting, an install fair, and a job fair for all of the
computer programming hopefuls. LinuxExpo '97 will be complete with
refreshments and entertainment from the Class Action Jugglers.
For addtional information: Anna Selvia, anna@linuxexpo.org
LinuxExpo '97 Technical Conference, www.linuxexpo.org
3201 Yorktown Ave. Suite 113
Durham, NC 27713
_____________________________________________________________
WWW: LINUX ARCHIVE SEARCH SITE
Date: Thu, 21 Nov 1996
Tired of searching sunsite or tsx-11 for some program you heard
about on irc? Well, the Linux Archive Search (LAS) is here. It is
a search engine that searches an updated database of the files
contained on sunsite.unc.edu, tsx-11.mit.edu, ftp.funet.fi, and
ftp.redhat.com. You can now quickly find out where the files are
hiding! The LAS is living at http://torgo.ml.org/las (It may take
a second to respond, its on a slow link). So give it a whirl, who
knows, you may use it a lot!
For additional information:
Jeff Trout, threshar@serve.com
The Internet Access Company, Inc.
_____________________________________________________________
NETHERLANDS - LINUX BOOK ON-LINE
Date: Thu, 05 Dec 1996
The very first book to appear in Holland on the Linux operating
system has gone on-line and can be found at:
http://www.cv.ruu.nl/~eric/linux/boek/
And of course from every (paper) copy sold, one dollar is sent to
the Free Software Foundation. For additional information:
Hans Paijmans, KUB-University, Tilburg, the Netherlands
paai@kub.nl , http://purl.oclc.org/NET/PAAI/
_____________________________________________________________
NEW O'REILLY LINUX WWW SITE
Date: 26 Nov 1996
Check out the new O'Reilly & Associates, Inc. Linux web site at
http://www.ora.com/info/linux/
It has:
+ Free excerpt from Linux Multimedia Guide
+ Interview with Olaf Kirch
+ Recommended links to the best Linux web sites.
+ Links to our Unix & Linux book pages
For additional information:
O'Reilly & Associates, Inc., john@ora.com
_____________________________________________________________
PCTV REMINDER
The "Unix III - Linux" show will air on the Jones Computer Network
(JCN) and the Mind Extension University Channel (MEU) the week of
January 20, 1997.
The scheduled times are:
+ Mon. 11:30 PM - 12:00 AM
+ Wed. 9:30 PM - 10:00 PM
+ Thu. 11:30 PM - 12:00 AM
+ Fri. 9:30 PM - 10:00 PM
+ Sun. 9:30 PM - 10:00 PM
This show will also air on the NBC Superchannel (CNBC) January 25,
1997.
It is best to call your local cable operator to find the
appropriate channel.
Tom Schauer, Production Assoc. PCTV
_____________________________________________________________
SOFTWARE ANNOUNCEMENTS
_____________________________________________________________
DAVINCI V2.0.2 - GRAPH VISUALIZATION SYSTEM
November 20, 1996 (Bremen, Germany) - The University of Bremen
announces daVinci V2.0.2, the new edition of the noted
visualization tool for generating high-quality drawings of
directed graphs with more than 2000 installations worldwide. Users
in the commercial and educational domain have already integrated
daVinci as user interface for their application programs to
visualize hierarchies, dependency structures, networks,
configuration diagrams, dataflows, etc. daVinci combines
hierarchical graph layout with powerful interactive capabilities
and an API for remote access from a connected application. In
daVinci V2.0.2, a few extensions related to improving performance
and usage of the previous V2.0.1 release have been made based on
user feedback.
daVinci V2.0.2 is licensed free of charge for non-profit use and
is immediately available Linux. The daVinci system can be
downloaded with this form:
http://www.informatik.uni-bremen.de/~davinci/daVinci_get_daVinci.h
tml
For additional information:
Michael Froehlich, daVinci Graph Visualization Project
Computer Science Department, University of Bremen, Germany
http://www.informatik.uni-bremen.de/~davinci ,
daVinci@Informatik.Uni-Bremen.DE
_____________________________________________________________
WWW: GETWWW 1.3 - DOWNLOAD AN ENTIRE HTML SOURCE TREE
Date: Wed, 04 Dec 1996
Getwww is designed to download an entire HTML source tree from a
remote URL, recursively changing image and hypertext links.
From the LSM:
Primary-site: ftp.kaist.ac.kr /incoming/www 25kB
getwww++-1.3.tar.gz
Alternate-site: sunsite.unc.edu
/pub/Linux/system/Network/info-systems/www 25kB
getwww++-1.3.tar.gz
Platform: Linux-2.0.24
Copying-policy: GPL
For additional information:
In-sung Kim, Network Tool Group, kisskiss@soback.kornet.nm.kr
_____________________________________________________________
MOTIF INTERFACE BUILDER ON UNIFIX 2.0
Date: Sun, 01 Dec 1996
Unifix Software GmbH is proud to announce View Designer/X, a new
Motif interface builder available for Linux. A demo version of VDX
is included on Unifix Linux 2.0.
With object oriented and interactive application development
tools, the software developer is able to design applications with
better quality and in shorter times.
For more information and to download the latest demo version, see:
http://www.unifix.de/products/vdx
For additional information: Unifix Software GmbH, info@unifix.de
_____________________________________________________________
VIEW DESIGNER/X
Date: Fri, 13 Dec 1996
View Designer/X, a new Motif Interface Builder for Linux has been
released. It enables application developers to design user
interfaces with Motif 2.0 widgets and to generate C and C++ code.
The VDX provides an interactive Wysiwyg View and a Widget Tree
Browser which can be used to modify the structure of the user
interface. All resources are adjustable by Widget Resource Editor
and by using template files the code generation of VDX is more
flexible than those of other interface builders.
Bredex GmbH, Germany is distributing the View Designer/X via Web
service. Please see following web page for more information and
downloading the free demo version:
http://www.bredex.de/EN/vdx/
Dirk Laessig, dirk@unifix.de
_____________________________________________________________
X-FILES 1.21 - GRAPHICAL FILE MANAGER IN TCL/TK
Date: Sun, 01 Dec 1996
X-Files is a graphical file management program for Unix/X-Window
environment developed on Linux.
For more information and packages see:
http://pinhead.tky.hut.fi/~xf_adm/
http://www.hut.fi/~mkivinie/xfindex.html
java.inf.tu-dresden.de:/pub/unix/x-files
For questions:
xf_adm@pinhead.tky.hut.fi
For additional information:
Mikko Kiviniemi, mkivinie@cc.hut.fi , jforsten@cc.hut.fi
Helsinki University of Technology
_____________________________________________________________
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_____________________________________________________________
This page written and maintained by the Editor of Linux Gazette,
gazette@ssc.com
Copyright &copy; 1997 Specialized Systems Consultants, Inc.
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
THE ANSWER GUY
By James T. Dennis, jimd@starshine.org
_____________________________________________________________
CONTENTS:
8. Dialup Problem
9. File Referencing
10. Combining Modems for More Speed
11. WWW Server
_____________________________________________________________
COMBINING MODEMS FOR MORE SPEED
Date: Mon, 23 Dec 1996 23:37:00 -0800 (PST)
From: liberty@pe.net (Keith)
Thanks for reading this post. I have heard that it's possible to
set up Linux to combine two analog modems into one so as to double
the speed of a connection. Is this true, how does this work and
where can I get more info, guidance, how-to, etc.? I have
Slackware 96 from Infomagic. Your truly, Keith Bell
I've heard of this as well. I've never used it but let's look it
up...
Ahh... that would be the EQL option in the kernel. Here's an
excerpt from the 'make menuconfig' help pages (in the 2.0.27 kernel
sources):
Linux Kernel v2.0.27 Configuration
EQL (serial line load balancing) support:
If you have two serial connections to some other computer (this
usually requires two modems and two telephone lines) and you use
SLIP (= the protocol for sending internet traffic over telephone
lines) or PPP (= a better SLIP) on them, you can make them behave
has to be supported at the other end as well, either with a similar
EQL Linux driver or with a Livingston Portmaster 2e. Say Yes if you
want this and read drivers/net/README.eql.
So that file is :
EQL Driver: Serial IP Load Balancing HOWTO
Simon "Guru Aleph-Null" Janes, simon@ncm.com
v1.1, February 27, 1995
(After reading this you'll know about as much on this subject as I
do -- after using any of this you'll know *much* more).
_____________________________________________________________
DIALUP PROBLEM
Date: Tue, 31 Dec 1996 05:13:51 -0800 (PST)
From: gekko@midusa.net
I don't know if you can, or even are willing, help me witha
problem i have. I'm running redhat 4.0, on a p120 w/24 megs of
ram, kernel 2.0.18
I'm willing.
anyway...i have this ppp connection problem and no I know knows what
the problem is, i've looked through the FAQS, HOWTO's, tried
#linux on irc, etc etc...no one knows what my problem is, so now
i'm desperate.
When i try to dial my isp, i get logged in fine, but its REALLY
slow. i'm using the 'network module' ppp thing in control panel on
X. mru=1500, asyncmap=0,speed=115000, i couldn't find a place to
insert mtu, and when i tried putting that in /etc/ppp/options the
script this program was using wouldn't work.
Usually I see these symptoms when there is an IRQ conflict. Some of
the data gets through -- with lots of errors and lots of
retransmits but any activity on the rest of the machine -- or even
just sitting there -- and you get really bad throughput and very
unreliable connections.
I noticed that after i input something and then move the cursor off of
the windows, it runs at a much faster speed, and it gets annoying
moving the cursor back and forth. I tried dip, minicom, and this
'network module' thing...all are slow
I would do all of your troubleshooting from outside of X. Just use
the virtual consoles until everything else works right. (Fewer
layers of things to conflict with one another).
if you can shed any light on this, it would be much appreciated.
thanks
Take a really thorough look at the hardware settings for everything
in the machine. Make a list of all the cards and interfaces -- go
through the docs for each one and map out which ones are using
which interfaces.
I ended up going through several combinations of video cards and
I/O cards before I got my main system all integrated. Luckily newer
systems are getting better (this is a 386DX33 with 32Mb of RAM and
a 2Mb video cards -- two IDE's, two floppy drives, two SCSI
hardisks, an internal CD-ROM, and external magneto optical drive, a
serial mouse, a modem (used for dial-in dial-out, uucp, and ppp)
and null modem (I hook a laptop to it as a terminal for my wife)
and an ethernet card.
Another thing to check is the cabling between your serial connector
and your modem. If you're configured for XON/XOFF you're in
trouble. If you're configured for hardware flow control and you
don't have the appropriate wires in your cable than you're in worse
trouble.
Troubleshooting of this sort really is best done over voice or in
person. There are too many steps to the troubleshooting and testing
to do effectively via e-mail.
_____________________________________________________________
FILE REFERENCING
Date: Wed, 18 Dec 1996 00:16:42 -0800 (PST)
> "A month of sundays ago L.U.S.T List wrote:"
>> 1. I do not know why on Linux some program could not run
>> correctly.
>> for example
>> #include
>> main()
>> {
>> printf("test\n");
>> fflush(stdout);
>> }
>> They will not echo what I print.
>
> Oh yes it will. I bet you named the executable "test" ... :-)
> (this is a UNIX faq).
>
I really suggest that people learn the tao of "./"
This is easy -- any time you mean to refer to any file in the
current directory precede it with "./" -- this forces all common
Unix shells to refer to the file in THIS directory. It solves all
the problems with files that start with dashes and it allows you to
remove :.: from your path (which *all* sysadmins should do right
NOW).
That is the tao of "./" -- the two keystrokes that can save you
many hours of grief and maybe save your whole filesystem too.
_____________________________________________________________
WWW SERVER?
Date: Tue, 31 Dec 1996 05:19:11 -0800 (PST)
From: (Paulo Marcio Villaca Veiga) paulom@cedro.fisica.ufmg.bri
Where can I get (or buy) a WWW server for LINUX?
Please, help me.
Web servers are included with most distributions of Linux. The most
popular one right now is called Apache. You can look on your CD's
(if you bought a set) or you can point a web client (browser) at
http://www.apache.org for more information and for an opportunity
to download a copy.
There are several others available -- however Apache is the most
well known -- so it will be the best for you to start with. It is
also widely considered to offer the best performance and feature
set (of course that is a matter of considerable controversy among
"connosieurs" just as is the ongoing debate about 'vi' vs.
'emacs').
thank you
You're welcome.
_____________________________________________________________
Copyright &copy; 1997, James T. Dennis
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
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_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
COMDEX '96
By Belinda Frazier and Kevin Pierce
_____________________________________________________________
Comdex/Fall '96 has come and gone once again. COMDEX is the second
largest computer trade show in the world, offering multiple
convention floors with 2000 exhibitors plying their new computer
products to approximately 220,000 attendees in Las Vegas, Nevada
in November of 1996.
This year's show was a great success for Linux in general. The
first ever ``Linux Pavilion'' was organized at the Sands
Convention Center and Linux vendors from all over the country
participated. The Linux International (LI) booth was in the
center, giving away literature and information for all the Linux
Vendors. Linux International is a not-for-profit organization
formed to promote Linux to computer users and organizations.
Staffed by volunteers including Jon ``Maddog'' Hall and Steve
Harrington, the LI booth was a great place for people to go to
have their questions answered. Needless to say, the Linux
International Booth was never empty. Surrounding LI, were Red Hat
Software and WorkGroup Solutions.
Other vendors in the pavilion included Craftwork Solutions, DCG
Computers, Digital Equipment Corporation, Frank Kasper &
Associates, Infomagic, Linux Hardware Solutions, SSC (publishers
of Linux Journal), and Yggdrasil Computing. Caldera, Pacific
HiTech, and Walnut Creek both exhibited at Comdex, but not as part
of the Linux Pavilion.
SSC gave out Linux Journals at the show and actually ran out of
magazines early Thursday morning. Luckily, we were able to have
some more shipped to us, but we still ran out again on Friday, the
last day of the show. Comdex ran five full days and the Sands
pavilion was open from 8:30 to 6 most show days which meant long
days for all the exhibitors there.
Show management put up signs, directing attendees to the Linux
Pavilion and to "more Linux vendors". The show was so large that
it was easy to get lost.
At the LI booth and at SSC's booth, the response to Linux was
overwhelmingly positive. Questions ranged from ``I've heard a lot
about Linux, but I'm not sure what it is, can you enlighten me?''
to ``I haven't checked for a few days---what is the latest
development kernel?''
For next year's Comdex in November '97, Linux vendors, coordinated
by Linux International, are already working to put together a
Linux pavilion at least three times as big as the one this year.
Vendors interested in being part of the Linux pavilion in November
'97 may contact Softbank who put on Comdex at mandino@comdex.com
or to do this through Linux International, contact ``Jon Maddog''
Hall via e-mail at maddog@zk3.dec.com.
_____________________________________________________________
Copyright &copy; 1997, Belinda Frazier & Kevin Pierce
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
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_____________________________________________________________
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
FILTERING ADVERTISEMENTS FROM WEB PAGES USING IPFWADM
By David Rudder drig@magicweb.com
_____________________________________________________________
Lately, a lot of Web pages have begun selling ad space "banners."
Wasting valuable bandwidth, these banners often hawk products I
don't care to hear about. I'd rather not see them, and not have to
download their contents.
There are two ways of filtering out these banners. The first is to
deny all pictures that are wider than tall and generally towards
the top or bottom of the page. The second is to simply block all
the accesses to and from the web sites that are the notorious
advertisers. This second approach is the one I'm going to take.
When searching around the web, you will see that many of the
banners come from the site ad.linkexchange.com. This is the site
we will want to ban.
_____________________________________________________________
SETTING UP YOUR FIREWALL
Our first order of business is to set up our firewall. We won't be
using it for security, although this doesn't prohibit also using
the firewall for security. First, we recompile the kernel, saying
"Yes" to CONFIG_FIREWALL. This allows us to use the built in
kernel firewalling.
Then, we need to get the IPFWADM utility. You can find it at:
http://www.xos.nl/linux/ipfwadm . Untar, compile and install
this utility.
Since we are doing no other firewalling, this should be
sufficient.
_____________________________________________________________
BLOCKING UNWANTED SITES
Now, we come to the meat of the maneuver. We need now to block
access to our machine from ad.linkexchange.com. First, block out
access to the sight, so that our requests don't even make it
there. ipfwadm -O -a reject -P tcp -S 0.0.0.0/0 -D
ad.linkexchange.com 80
This tells ipfwadm to append a rule to the Output filter. The rule
says to reject all packets of protocol TCP from anywhere to
ad.linkexchange.com on port 80. If you don't get this, read Chris
Kostick's excellent article on IP firewalling at
http://www.ssc.com/lj/issue24/1212.html.
The next rule is to keep any stuff from ad.linkexchange.com from
coming in. Technically, this shouldn't be necessary. If we haven't
requested it, it shouldn't come. But, better safe than sorry.
ipfwadm -I -a reject -P tcp -S ad.linkexchange.com 80 -D 0.0.0.0/0
Now, all access to and from ad.linkexchange.com is rejected.
Note: this will only work when web browsing from that machine. To
filter for a whole network, do them same but with -F instead of -O
and -I.
_____________________________________________________________
TESTING IT OUT
To test, visit the site http://www.reply.net. They have a banner
on top which should either not appear or appear as a broken icon.
Either way, no network bandwidth will be wasted downloading the
picture, and all requests will be rejected immediately.
_____________________________________________________________
FILLING IT OUT
Not all banners are so easily dealt with. Many companies, like
Netscape, host their own banners. You don't want to block access
to Netscape, so this approach won't work. But, you will find a
number of different advertisers set up like linkexchange. As you
find more, add them to the list of rejected sites. Good luck, and
happy filtering!
_____________________________________________________________
Copyright &copy; 1997, David Rudder
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
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_____________________________________________________________
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
FLOPPY DISK TIPS
By Bill Duncan, VE3IED, bduncan@beachnet.org
_____________________________________________________________
Although more computers are becoming network connected every day,
there are many instances where you need to transfer files by the
ol' sneaker-net method. Here are some hints, tips and short-cuts
for doing this, aimed at users who are new to Linux or Unix.
(There may even be some information useful to old-timers...)
+ Formatting, Filesystems and Mounting
+ Backups, Cpio and Gzip
+ Floppy as a Raw Device for Large Files or Directories
+ Miscellaneous
What do I use floppies for? As a consultant, I frequently do
contract work for companies which, because of security policies,
do not connect to the 'Net. So, FTP'ing files which I need from my
network at home is out of the question.
My current contract as an example, I am using Linux as an
X-Windows terminal for developing software on their DEC Alphas
running OSF. (I blew away the Windoze '95 which they had loaded on
the computer they gave me.) I often need to bring files with me
from my office at home, or backup my work to take back home for
work in the evening. (Consultants sometimes work flex-hours, which
generally means more hours...)
Why use cpio(1) or tar(1) when copying files? Because it is a
portable method of transferring files from a group of
subdirectories with the file dates left intact. The cp(1) command
may or may not do the job depending on Operating Systems and
versions you are dealing with. In addition, specifying certain
options will only copy files which are new or have changed.
_____________________________________________________________
Formatting, Filesystems and Mounting
_____________________________________________________________
The first thing you need to do to make the floppies useful is to
format them, and usually lay down a filesystem. There are also
some preliminary steps which make using floppy disks much easier,
which is the point of this article.
I find it useful to make my username part of the floppy group in
the /etc/group file. This saves you from needing to su to root
much of the time. (You will need to log out and log back in again
for this to take effect.) I also use the same username both on the
client's machine and my home office which saves time. The line
should now look like this:
floppy::11:root,username
The following setup is assumed for the examples I present here.
The root user must have the system directories in the PATH
environment variable. Add the following to the .profile file in
/root if not already there by su'ing to root.
su - # this should ask for the root password.
cat >> .profile
PATH=/sbin:/usr/sbin:$PATH
<ctrl>-D
You can also use your favorite editor to do this... I prefer vim(1)
and have this symlinked to /usr/bin/vi instead of elvis(1) which
is usually the default on many distributions. VIM has online help,
and multiple window support which is very useful! (A symlink is
created with a -s option to ln(1), and is actually called a
symbolic link.)
Next, add the following lines to the /etc/fstab file: (I have all
the user mountable partitions in one place under /mnt. You may
want a different convention, but this is useful. I also have
/mnt/cdrom symlinked to /cd for convenience.)
/dev/fd0 /mnt/fd0 ext2 noauto,user 1 2
Still logged in as root, make the following symlink: (If you have
more than one floppy drive, then add the floppy number as well.)
ln -s /mnt/fd0 /fd
-or-
ln -s /mnt/fd0 /fd0
These two things make mounting and unmounting floppies a cinch. The
mount(8) command follows the symlink and accesses the /etc/fstab
file for any missing parameters, making it a useful shortcut.
To make the floppy usable as an ext2fs Linux filesystem, do the
following as root: (The username is whatever username you use on
regularly on the system. You, of course, should not use the root
user for normal use!)
export PATH=/sbin:/usr/sbin:$PATH # not needed if you set environment
fdformat /dev/fd0
mke2fs /dev/fd0
mount /dev/fd0 /mnt/fd0
chown username /mnt/fd0
You may need to specify the geometry of the floppy you are using. If
it is the standard 3.5 inch double sided disk, you may need to
substitute /dev/fd0H1440 for the device name (in 1.2.x kernels).
If you have a newer 2.xx kernel and superformat(1), you may want
to substitute this for fdformat. See the notes in the
Miscellaneous section below, or look at the man page. You may
now exit out of su(1) by typing:
exit
From this point on, you may use the mount(8) and umount(8)
commands logged in as your normal username by typing the
following:
mount /fd
umount /fd
_____________________________________________________________
Backups, Cpio and Gzip
_____________________________________________________________
For backing up my work to take home or to take back to the office
I use cpio(1) instead of tar(1) as it is far more flexible, and
better at handling errors etc. To use this on a regular basis,
first create all the files you need by specifying the command
below without the -mtime -1 switch. Then you can make daily
backups from the base directory of your work using the following
commands:
cd directory
mount /fd
find . -mtime -1 -print | cpio -pmdv /fd
sync
umount /fd
When the floppy stops spinning, and the light goes out, you have
your work backed up. The -mtime option to find(1) specifies files
which have been modified (or created) within one day (the -1
parameter). The options for cpio(1) specify copy-pass mode, which
retain previous file modification times, create directories where
needed, and do so verbosely. Without a -u (unconditional) flag, it
will not overwrite files which are the same age or newer.
This operation may also be done over a network, either from NFS
mounted filesystems, or by using a remote shell as the next
example shows.
mount /fd
cd /fd
rsh remotesystem '(cd directory; find . -mtime -1 -print | cpio -oc)' |
cpio -imdcv
sync
cd
umount /fd
This example uses cpio(1) to send files from the remote system, and
update the files on the floppy disk mounted on the local system.
Note the pipe (or veritical bar) symbol at the end of the remote
shell line. The arguments which are enclosed in quotes are
executed remotely, with everything enclosed in braces happening in
a subshell. The archive is sent as a stream across the network,
and used as input to the cpio(1) command executing on the local
machine. (If both systems are using a recent version of GNU cpio,
then specify -Hcrc instead of c for the archive type. This will do
error checking, and won't truncate inode numbers.)
The remote system would have: cpio -oHcrc
and the local side would have: cpio -imdvHcrc
To restore the newer files to the other computer, change
directories to the base directory of your work, and type the
following:
cd directory
mount -r /fd
cd /fd
find . -mtime -1 -print | cpio -pmdv ~-
cd -
umount /fd
If you needed to restore the files completely, you would of course
leave out the -mtime parameter to find(1).
The previous examples assume that you are using the bash(1) shell,
and uses a few quick tricks for specifying directories. The "~-"
parameter to cpio is translated to the previous default directory.
In other words, where you were before cd'ing to the /fd directory.
(Try typing: echo ~- to see the effect, after you have changed
directories at least once.) The cd ~- or just cd - command is
another shortcut to switch directories to the previous default.
These shortcuts often save a lot of time and typing, as you
frequently need to work with two directories, using this command
to alternate between them or reference files from where you were.
If the directory which you are tranferring or backing up is larger
than a single floppy disk, you may need to resort to using a
compressed archive. I still prefer using cpio(1) for this,
although tar(1) will work too. Change directories to your work
directory, and issue the following commands:
cd directory
mount /fd
find . -mtime -1 -print | cpio -ovHcrc | gzip -v > /fd/backup.cpio.gz
sync
umount /fd
The -Hcrc option to cpio(1) is a new type of archive which older
versions of cpio might not understand. This allows error checking,
and inode numbers with more than 16 bits.
Of course, your original archive should be created using find(1)
without the -mtime -1 options.
_____________________________________________________________
Floppy as a Raw Device for Large Files or Directories
_____________________________________________________________
Sometimes it is necessary to backup or transfer a file or
directories which are larger than a floppy disk, even when
compressed. For this, we finally need to resort to using tar.
Prepare as many floppies as you think you'll need by using the
fdformat(8) command. You do not need to make filesystems on them
however, as you will be using them in raw mode.
If you are backing up a large set of subdirectories, switch to the
base subdirectory and issue the following command:
cd directory
tar -cv -L 1440 -M -f /dev/fd0 .
This command will prompt you when to change floppies. Wait for the
floppy drive light to go out of course!
If you need to backup or transfer multiple files or directories,
or just a single large file, then specify them instead of the
period at the end of the tar command above.
Unpacking the archive is similar to the above command:
cd directory
tar -xv -L 1440 -M -f /dev/fd0
_____________________________________________________________
Miscellaneous
_____________________________________________________________
Finally, here are some assorted tips for using floppies.
The mtools(1) package is great for dealing with MS-DOG floppies,
as we sometimes must. You can also mount(8) them as a Linux
filesystem with either msdos or umsdos filesystem types. Add
another entry to the /etc/fstab entry you made before, so that the
two lines will look like this:
/dev/fd0 /mnt/fd0 ext2 noauto,user 1 2
/dev/fd0 /mnt/dos msdos noauto,user 1 2
You can now mount an MS-DOS floppy using the command:
mount /mnt/dos
You can also symlink this to another name as a further shortcut.
ln -s /mnt/dos /dos
mount /dos
The danger of using the mount(8) commands rather than mtools(1)
for users who are more familiar with MSDOS, is that you need to
explicitly unmount floppies before taking them out of the drive
using umount(8). Forgetting this step can make the floppy
unusable! If you are in the habit of forgetting, a simple low-tech
yellow Post-it note in a strategic place beside your floppy drive
might save you a few headaches. If your version of Post-it notes
has the <BLINK> tag, use it! ;-)
"umount me first!"
Newer systems based on the 2.xx kernel are probably shipped with
fdutils. Check to see if you have a /usr/doc/fdutils-xxx
directory, where xxx is a version number. (Mine is 4.3). Also
check for the superformat(1) man page. This supersedes fdformat(1)
and gives you options for packing much more data on floppies. If
you have an older system, check the
ftp://ftp.imag.fr/pub/Linux/ZLIBC/fdutils/ ftp site for more
information.
The naming convention for floppies in newer 2.xx kernels has also
changed, although the fd(4) man page has not been updated in my
distribution. If you do not have a /dev/fd0H1440 device, then you
probably have the newer system.
_____________________________________________________________
Copyright &copy; 1997, Bill Duncan
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Back Next
_____________________________________________________________
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
Welcom to the Graphics Muse Set your browser to the width of the
line below for best viewing.
&copy 1996 by mjh
_____________________________________________________________
--> Button Bar --> muse:
1. v; to become absorbed in thought
2. n; [ fr. Any of the nine sister goddesses of learning and the
arts in Greek Mythology ]: a source of inspiration
W elcome to the Graphics Muse! Why a "muse"? Well, except for the
sisters aspect, the above definitions are pretty much the way I'd
describe my own interest in computer graphics: it keeps me deep in
thought and it is a daily source of inspiration.
[Graphics Mews] [Musings] [Resources] indent T his column is
dedicated to the use, creation, distribution, and dissussion of
computer graphics tools for Linux systems.
Last month I introduced a new format to this column. The
response was mixed, but generally positive. I'm still getting more
comments on the format of the column rather than the content. I
don't know if this means I'm covering all the issues people want
to hear about or people just aren't reading the column. Gads. I
hope its not the latter.
This months issue will include another book review, a
discussion on adding fonts to your system, a Gimp user's story,
and a review of the AC3D modeller. The holiday season is always
busy one for me. I would have liked to do a little more, but there
just never seems to be enough time in the day. Graphics Mews
Disclaimer: Before I get too far into this I should note
that any of the news items I post in this section are just that -
news. Either I happened to run across them via some mailing list I
was on, via some Usenet newsgroup, or via email from someone. I'm
not necessarily endorsing these products (some of which may be
commercial), I'm just letting you know I'd heard about them in the
past month.
I went wondering through a local computer book store this
month and scanned the graphics texts section. I found a few new
tidbits that might be of interest to some of you.
3D Graphic File Formats: A Programmers Reference
Keith Rule has written a new book on 3D Graphics File Formats.
The book, which contains over 500 pages, has been published by
Addison-Wesley Developers Press and is listed at $39.95. It
includes a CD-ROM with a software library for processing various
3D file formats (both reading and writing), but the code is
written for MS systems. Keith states there isn't any reason why
the code shouldn't be portable to other platforms such as Linux.
Any takers out there?
ISBN 0-201-48835-3 indent indent
OpenGL Programming for the X Window System
I noticed a new text on the shelf of a local book store
(Softpro, in Englewood, Colorado) this past month - Mark J.
Kilgard's OpenGL Programming for the X Window System. This book,
from Addison Wesley Developers Press, appears to have a very good
coverage of how to write OpenGL applications that make use of X
Windows API's. I haven't read it yet (or even purchased it - yet,
but I will) so can't say how good it is. Mark is the author of the
GLUT toolkit for OpenGL. GLUT is to OpenGL what Xt or Motif is to
Xlib. Well, sort of. indent
Fast Algorithms for 3D-Graphics
This book, by Georg Glaeser and published by Springer, includes
a 3.5" diskette of source for Unix systems. The diskette, however,
is DOS formatted. All the algorithms in the text are written using
pseudocode, so readers could convert the algorithms to the
language of choice. indent indent
ImageMagick 3.7.8 released, including a new set of image library plug-ins
A new release of ImageMagick has been released from Alexander
Zimmermann. This release includes a "Plug In" library containing
the various image libraries ImageMagick needs to run. Alexander
has uploaded this new release to Sunsite as well as ImageMagick's
Web site. indent
MpegTV Player v0.9
A new version of the MpegTV Player has been released. This
version now includes audio support. indent indent
Imaging Technology Inc. IC-PCI frame grabber board driver
The second public release (v 0.2.0) of a kernel module for the
Imaging Technology Inc. IC-PCI frame grabber board (rev 1) and the
AM-VS acquisition module has been released. This driver is
maintained by GOM mbH (Gesellschaft fuer optische Messtechnik) TU
Braunschweig, Institute for Experimental Mechanics. A full motion
video test program and a read function for original camera files
are included.
Author: Matthias Stein
Maintained by: Dirk Bergmann
This software is not really free (see the LICENSE file). indent
Viewmol 2.0 released
I don't know much about this tool, but it appears to have alot
of graphics related features, so I thought I'd mention it here.
The LSM gives the following information:
Viewmol is a program for the visualization of outputs from quantum
chemical as well as from molecular mechanics programs. Currently
supported are Gaussian 9x, Discover, DMol/DSolid, Gulp, Turbomole,
and PDB files. Properties visualized include geometry (with
various drawing modes), vibrations (animated or with arrows),
optimization history/MD trajectories, MO energy level diagram,
MOs, basis functions, electron density. Drawings can be saves as
TIFF, HPGL, Postscript, input files for Rayshade.
ftp://ftp.ask.uni-karlsruhe.de/pub/education/chemistry/viewmol-2.0
.tgz indent indent indent
Did You Know?
3D Site (http://www.3dsite.com/3dsite) is a Web site devoted to
everything 3D. There are job postings, links to free repositories
of 3D models and lots of other valuable information.
3D Cafe (http://156.46.199.2/3dcafe/) is another Web site
with various useful 3D information. It also maintains a large
collection of DXF and 3DS model files.
An Important Survey
I've been talking to a couple of publishers about doing a book
aimed at Linux users. I'd like to write a User's Guide for the
Gimp but the publisher feels a more general text on doing
Web-based graphics might have a wider appeal (face it - the Linux
audience just isn't the size of the MS audience - yet - but the
publishers are considering both types of books). I told them I'd
ask my readers which type of text they'd like to see. The Gimp
book would include details on how to use each of the applications
features as well as a number of tutorials for doing various types
of effects. The book on doing graphics for Web pages would include
discussions on using HTML, information on tools besides the Gimp
and a few case studies (including something on animation).
However, the Web book wouldn't go into as much detail for each of
the tools. That information would be more general in nature.
I don't have a server to run any CGI scripts to register
votes, so simply mail me with your opinions. Thanks!
A Call for Help
I plan on covering more 3D tools in the future, but I have to
learn to use them first. The next tool I'm going to look into is
BMRT. If you use BMRT and want to help me get started drop me a
line. I'd like to do an introduction to BMRT in the March issue
if possible but I want to make sure I know what I'm talking about
first. Thanks! indent indent indent
Musings
A Gimp User's Story (or "Why I Use the Gimp")
The following piece was posted on the Gimp User's Mailing list by
Mike Phillips.
At work, we have a "Library News Network", which is actually
a 386 pc running a TV via a video converter in a continual
slideshow with information about upcoming events in the law
library and the law school. Last year, my boss did some stuff in
Freelance Graphics which, quite frankly, was rather limited in
effect.
This year, it's my baby, and I'm making the slideshow
(640x480x256 GIF files, run by a simple DOS program and looped by
a batch file) in the GIMP. Here are some things I've done to make
the text more readable and make the display reasonably
eye-catching. Nothing fancy, but hopefully the tricks will give
other people ideas to play with on their own.
First, don't use a plain background. The blend tool is very
nice for this, and shaded green or blue with bright text is rather
nice looking. Start with a color and add some noise Create a blend
image of the same size and multiply by the image with noise. This
creates a very cool background for a slide. Better yet, if there's
an appropriate photograph, use it! (I used a gorgeous picture of
Yosemite Park to announce an environmental law symposium, and a
decent photo of the U.S. Supreme Court justices to announce our
Supreme Court Preview.)
On the subjects of backgrounds, since I don't remember
seeing this tip, here's a quickie for clouds: Make a plasma of the
appropriate size, grayscale it, convert it back to color, and
Brightness/Contrast/Gamma it into submission. I usually knock the
brightness up about 75-100, and the blue up to around 5 and the
green to about 2. Instant pretty sky (Obviously, skies from other
planets could be done with reds and greens and whatnot.)
For the text, nothing beats some good fonts. Hit a font
archive, or buy a $10-$15 CD filled with fonts. Granted, I have
the Caldera Network Desktop, so I can use some fonts that (I
think) XFree can't, thanks to the font server, but it's worth a
shot. I got a CD with 1250 fonts for $13. [Ed. Next month I'll
cover how to add fonts to your system so you can use them with the
Gimp. mjh]
Here's a variation on the rounded-text tips: work out your
text, then Duplicate it once and Offset it once (say 4x4). Edge
Detect then Invert the duplicate and Gaussian Blur the offset
twice. Multiply the resulting images, and use the original as a
mask to composite something else over the image resulting from the
multiplication. Very nice, edged & floating/shadowed text. Shows
up great on a TV monitor.
For the text, use any appropriate single color. Bright
colors and high contrast work very well for what I do, although
I've played with textures, rippled blends, plasma clouds, and
what-not.
Of course, it can be spiced up with all sorts of clipart (I
heartily recommend Barry's Clipart Server (www.barrysclipart.com),
from which I shamelessly borrow, and voila, instant slideshow!
I have left our Fall Break edition of the LNN at:
http://www.lawlib.wm.edu/LNN-old/. if you want to see some of
what can be done with it. You might be better off watching the
show when the graphics aren't resized to 320x240. Also, the latest
version of these is available at http://www.lawlib.wm.edu/LNN/.
[Ed. Later Mike posted another message that included some
interesting effects. I thought it might be appropriate to include
them with his other posting.]
Recently, while wandering through the plug-ins available, I
found the charcoal plug-in. Compiled it, added it, used it. Rather
nifty, actually. However, it got me thinking and experimenting,
and I produced two potentially interesting effects:
(1) Pastel sketch: Take a color (RGB) image, Edge-detect it,
Invert, and (optionally) contrast autostretch. On many images,
this will produce a nifty pastel sketch. If the image is too high
of detail, degrade the color or pixelize it first, otherwise you
may end up with too many extraneous lines.
(2) Watercolor sketch: Take a color (RGB) image, make a grayscale
of it. Edge Detect the grayscale (this will give you the sketch
lines); this can be hard to balance the way you want, so you may
want to threshold it or pixelize the image first. Then, pixelize
and degrade the main image to 32 colors (16 or 20 works even
better). Eliminate the background you don't want, Gaussian blur it
a few times, and brighten it some. Multiply the edging onto it.
Voila; (nearly) instant watercolor, akin to the court sketches on
news shows.
Mike Phillips, mike@lawlib.wm.edu indent
Jim Blinn's Corner - A Trip Down the Graphics Pipeline
indent I am not formally trained in computer graphics (1). Everything
I know I've learned in the last year or so by reading, examining
source code, and through the kind assistance of many members of
the Net. So my ability to understand some of the more formal texts
on computer graphics is limited.
Given this limitation, I found I was still able to read and
comprehend a good portion of Jim Blinn's book Jim Blinn's Corner -
A Trip Down the Graphics Pipeline, which is a collection of
articles taken from his column in the IEEE Computer Graphics and
Applications journal. This book is the first of what may be two
books, assuming there is sufficient interest in the first book.
The second will cover a set of pixel arithmetic articles taken
from the same column.
In the preface Jim describes how he used a writing style
that is "certainly lighter than a typical SIGGRAPH paper, both in
depth and in attitude." I can't agree more. Computer graphics
should be a fun subject and, despite the math, this book does
provide a giggle here and there.
Don't get me wrong, though. There is plenty of the technical
details on how to compute positions in 3D space, perspective
shadows, and subpixelic particles. Hefty stuff for the beginner.
Nearly incomprehensible to the person who hasn't used matrix
arithmetic in the past 8 years. Still, chapters like The Ultimate
Design Tool (which talks about how an idea should start), and
Farewell to Fortran (which talks about using various languages
in computer graphics) provided enough non-mathematical discussions
to let my brain recover while still keeping my interest peaked.
I haven't read the book front to back yet. I'm saving whats
left (about half the book) for my 16 days of freedom scheduled to
start later this month. Its first on my reading list. Second will
be my college Linear Algebra text. The first half of Jim's book
reminded me about how much I'd forgotten in 8 years. Like the
saying goes, one must strive for the impossible before they know
what is possible. indent indent indent
More Musings...
+ Review: The AC3D Modeller - An introduction to the very nifty
3D modeller from Andy Colebourne. Warning: lots of images on
this page!
+ History of the Portable Network Graphics (PNG) format - A
detailed look at how an Internet-based cooperative effort
brought about this graphics file format specification.
indent indent indent
indent
The IRTC - A raytracing competition for the fun of it
indent F or the past few months, I've been helping to administer an
Internet-based competition for users of raytracing software. This
competition, the Internet Ray Tracing Competition or IRTC, is open
to anyone interested in creating 3D images using software on any
platform as long as the software falls within a few basic
guidelines. It is based on another competition started back in
1994 by Matt Kruse. Matt eventually had to close down the contest
due to the enormous amount of time it takes to run such a contest.
At the time, he was more or less doing all the work himself.
Earlier this year Chip Richards started to organize the
contest once again. A group of interested individuals signed up to
help out. In the end, most of us (myself included) provide only
organizational input - ideas for rules or input on rulings
regarding cheating (yes, there has been some of that), helping to
select topics, and so forth. Most of the real work has been done
by Chip, Bill Marrs, and Jon Peterson (although Jon has since had
to move on to other things).
The contest is made up independent rounds that last 2
months. Each round has a topic which entrants must use as the
basis for their images. Entries are supposed to be new images,
created during the span of the contest, however most people use
bits and pieces of older models that they or someone else has
created. The tools allowed vary but raytracing tools are preferred
and no post processing is allowed (for example, you can't add a
lens flare after the image has been rendered). Anyone is allowed
to vote (currently) on the images and winners receive small prizes
like CDs and prints of their images.
more IRTC... (same page as AC3D review)
Resources
The following links are just starting points for finding more
information about computer graphics and multimedia in general for
Linux systems. If you have some application specific information
for me, I'll add them to my other pages or you can contact the
maintainer of some other web site. I'll consider adding other
general references here, but application or site specific
information needs to go into one of the following general
references and not listed here.
Linux Graphics mini-Howto
Unix Graphics Utilities
Linux Multimedia Page
Future Directions
Next month:
+ TkPOV - a POV-Ray scene file editor
+ Book Review: 3D Graphic File Formats by Keith Rule
+ Adding fonts to your system
+ Gimp Tips
+ ...and lots more!
Let me know what you'd like to hear about!
_____________________________________________________________
1. Anyone having an extra, unclaimed scholarship in computer
graphics is encouraged to contact me. I give preference to
those who have them within commuting distance of Denver,
where I live.
_____________________________________________________________
Copyright &copy; 1997, Michael J. Hammel
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Back Next
_____________________________________________________________
_____________________________________________________________
More...
Musings
+ Review: The AC3D Modeller
+ more IRTC...
indent
&copy 1996 Michael J. Hammel indent
Review: The AC3D Modeller
There are only a few 3D modellers available for Linux: AMAPI
(which may now only be available for the Mac, based on one report
I've received), Midnight Modeller, SCED/SCEDA, and AC3D. Each of
these has its advantages and disadvantages. I've tried each of
these at least briefly. A couple, SCED and AC3D, I've used to
actually create scenes. Lets take a quick look at one of these -
AC3D. AC3D comes from Andy Colebourne. It is a shareware
modeller that comes in binary format only. It is available for
Linux, SGI's and Sun's (both SunOS and Solaris). Once registered
you have access to a private Web site from which you can download
the full version of the software. Documentation is a bit sparse (a
common problem with much of the software available for Linux, in
this authors opinion), consisting of about 12 or 13 pages
formatted in either HTML or Postscript. The distribution package
contains the binary, the HTML manual with a few images and a set
of object files that are necessary for packages which use the Mesa
Graphics Library, which AC3D does. AC3D
Figure 1: Example AC3D session (this is taken from the AC3D Web
site).
The interface consists of 4 view windows and a control
panel. There are 3 orthographic views and a 3D view. Changes in
one of the orthographic view windows are reflected in the other
views. Edits are not allowed in the 3D view. The 3D view can
provide wireframe, filled or textured surfaces. My system is not
quite fast enough to handle anything but the wireframe surface so
I won't be able to say much about the texturing features of the
modeller.
AC3D supports a number of import file formats, including DXF
and Lightwave files. It can export POV, RIB, VRML and a couple of
other formats. Since the modeller is a based on vertices (as
opposed to primitives like spheres or boxes) it is quite easy to
manipulate basic shapes into more complex ones. This can be a
disadvantage to those used to the CSG aspects of SCED or users of
POV-Ray, but it really doesn't take that long to get used to. Even
though the modeller bases its shapes on vertices, there are still
a collection of basic shapes provided: disk, line, box, sphere,
and mesh are just some of these. These shapes are displayed with a
given number of vertices. The number of vertices can be configured
and its possible to add more vertices where necessary.
One of the nicest features is the ability to extrude a
2D shape into 3 dimensions. Lets follow an example of this. First,
select the "ellipse" drawing function from the control panel and
create a stretched out ellipse in the XY orthographic view. AC3D
Figure 2: An ellipse Next, change the Edit type to "vertex"
in the control panel and select all the vertices on the lower half
of the ellipse (but not the ones on the end of the ellipse).
Delete these with the "delete" function in the control panel. Then
select the two lowest vertices and insert some new vertices (as
shown in Figure 3). AC3D
Figure 3: The ellipse has been halved and some new vertices added.
This next part is a little tricky. What you want to do is
select the vertices on each end of the object and move them, one
at a time, until you get a slightly rounded effect. Then select 4
or 5 of the vertices on the back end (the left side in Figure 4)
and strecth them out a little, to flatten the wings trailing edge.
Then get rid of the extra vertices along the bottom of the wings
edge by selecting them and using the "delete" function in the
control panel. The result should look something like Figure 4.
AC3D
Figure 4: The wing edge takes shape This isn't bad, but a
wing should be smoother around the top and edges, so change the
Edit type to "Object" and select the wing. Then use the "Spline
Surfaces" option from the Object pull-down menu. This adds a bunch
of new vertices to the object and creates a smoother line around
the wing. AC3D
Figure 5: Smoothing the wing edge. Now lets take this simple
shape and extrude it. Make sure the Edit type is still "Object"
and select the wing edge. We need to change to the XZ orthographic
view window. Up to this point we've been using the XY viewport.
Click on "Extrude" under the Mouse options in the control panel.
Grab the object in the XZ viewport and drag up. The original
points stay put and a new set of points is moved to where ever you
drag to. Once you let go of the mouse button you'll see the new
points get connected to their corresponding points on the original
object. Notice how the connecting lines aren't quite straight.
This would be bad for a real wing, so we'll straighten them out.
AC3D
Figure 6: The wing edge gets extruded. In this next figure,
the control panel was used to change the Edit mode to "vertices"
and the vertices on the new side of the extruded object have been
selected. Once selected, the "move" option under the Mouse
features allows the selected vertices to be moved as a group. When
these vertices are moved the lines connecting them to the opposite
end are redrawn. You can play with this a bit in order to get the
connecting lines to become straight. Note that its not absolutely
necessary to correctly align the two ends of the extruded object,
but this is one way to do so if you feel it necessary. AC3D
Figure 7: The ends of the extruded object are aligned. Now
switch back to the "object" Edit mode and select the object. The
bounding box (in green) has handles that can be grabbed to drag
the bounding box to resize the object. Use the middle top and
bottom handles to make the object wider in the XZ view. AC3D
Figure 8: Stretch the object a bit. Next, switch back to
"vertices" Edit mode and select the vertices on one end of the
object. Click on "Create Surface" under Functions in the control
panel. If the surface (as viewed in the 3D view) does not appear
solid you can select "Poly" under Surface to create a solid
surface to close the end of the object. Repeat this process for
the other end.
Viola! You've got a solid surfaced wing, just like the one
in Figure 9. (The grid is an option for the 3D view window and not
part of the image.) Of course, this is a pretty simplistic
example, but you should get the idea of how easy it is to create
shapes using AC3D. You'll need to export the file to POV or RIB
format and add some real textures to finish up the project, of
course. AC3D
Figure 9: The solid surfaced wing.
When I first started examining modellers I got my hands on
SCED, a nifty modeller from Stephen Chenney. One of the nice
features of SCED is that it is constraint based - you can join
objects using CSG and then constrain them to certain points. This
allows you to create an arm, for example, that can bend only at
the elbow. AC3D works similarly in that you can rotate any set of
points around a single point within one of the orthographic views.
For example, if I created an arm I could select "Rotate" from the
control panel and then use the mouse to rotate the arm around a
single point, such as the elbow, in one of the 2D view windows. If
I need it to move in 3D I need to do this type of rotation in 2 or
more of the 2D view windows. This process is a little different
than SCED, which can move objects in 3 dimensions, but the result
is the same. In fact, at times it can be a little easier to keep
your bearings using multiple rotations in 2D.
Since I've never used any of the modellers available for
other systems (such as high end modellers on SGI's or any of the
modellers available for Microsoft or Mac systems) I can't say how
well AC3D compares to them. I do know that I found the modeller
fairly easy to learn, but I tend to be more motivated than some
folks. AC3D could use some online help (whats the difference
between a "Poly" and a "Polyline", for example) and more detailed
documentation in general. It would also be nice to be able to
unhide selected objects instead of all hidden objects. Andy has
told me that a new version coming soon will include the ability to
specify the exact dimensions of a selected object or set of
vertices. This is a very important feature in my eyes. I tend to
like to use modellers to create individual objets and then use the
conditional constructs of POV-Ray to position multiple copies of
them, such as trees or rocks or houses. By constraining an object
to a unit size it makes it easier to position and resize objects
using POV-Ray.
Of all the modellers I've tried AC3D is probably the easiest
to use. Its ability to import formats like DXF gives it a step up
on SCED, although I really like the latter too. I don't
particularly mind that you don't get the source to AC3D since I'm
mostly interested in just using the modeller and not in developing
new features for it. It would be nice if there were a plug-in
interface, but I'm not such a power user yet that I need that
feature. Aside from a lack of detailed documentation, and a few
keystrokes that are already used by fvwm, I find the AC3D modeller
worth the registration price.
indent
more IRTC...
The contest started in earnest in May/June of 1996. The
topic then was Time and there were some stunning entries. In
July/August we had fewer entries, but the topic - Summer - was a
little tougher to nail down. In September/October we hit the
jackpot with Science Fiction. Well over 200 entries were submitted
for this round. Thats quite a difference from the 20-30 submitted
during Matt's original contests. Fortunately much of the work for
viewing, voting, and tabulating information has been automated.
The contest has been great fun and has been accompanied with
lively discussions on the associated irtc-l mailing list.
Unfortunately, there are always those that have to try to
ruin things for everyone else. We had some people submit images
that were fair but not likely winners. They then submitted
multiple votes. A vote consists of ratings of all the images with
values between 1-20 for each in 3 categories - needless to say
this takes awhile to accomplish. Any vote that does not include
ratings for all images is not counted in the final tally. The
multiple votes were done offline (which is permissable) and
submitted from different email accounts. The artists images
received very high marks while all the rest received very low
(within a very small range) ratings. Then they got some of their
friends to do the same thing. Beyond this, others have submitted
numerous entries that they had made in the past (prior to the
contest) that just happen to fit the category (how many 3D
artists, for fun or profit, have *never* made a space scene?) in
order to turn the contest into their own private gallery. The
spirit of the competition is lost on some people, I'm afraid.
I haven't done any of the automation nor have I worked on
the very nice web site for the contest. But I've watched Chip and
Bill do so. Its very frustrating knowing how much effort they put
into this, trying very hard not to give themselves or anyone else
unfair advantages and still make the contest fun for everyone only
to see someone still try to cheat the system. Why? For a couple of
CDs? Remember when the Internet was a friendly, honest place?
Still, the contest continues and the Admin Team is working
on ways of keeping the contest fun, open to participation, and
fair. The guys could use a new host for their contest. Walnut
Creek, the current host, appears to be limiting ftp connections
and the amount of disk space required for 200+ images can get
rather large.
If you are into 3D rendering for the fun of it you owe it to
yourself to take a shot at the IRTC. Its fun to see how your
images stack up against others. Many of the voters offer comments
on the images which can very useful in any future images you
render. Check our the IRTC Web Site to get more details and join
in!
indent &copy 1996 by Michael J. Hammel
_____________________________________________________________
More...
Musings
History of the Portable Network Graphics (PNG) format
by Greg Roelofs
Prehistory
The Story of PNG actually begins way back in 1977 and 1978
when two Israeli researchers, Jacob Ziv and Abraham Lempel, first
published a pair of papers on a new class of lossless
data-compression algorithms, now collectively referred to as
``LZ77'' and ``LZ78.'' Some years later, in 1983, Terry Welch of
Sperry (which later merged with Burroughs to form Unisys)
developed a very fast variant of LZ78 called LZW. Welch also filed
for a patent on LZW, as did two IBM researchers, Victor Miller and
Mark Wegman. The result was...you guessed it...the USPTO granted
both patents (in December 1985 and March 1989, respectively).
Meanwhile CompuServe--specifically, Bob Berry--was busily
designing a new, portable, compressed image format in 1987. Its
name was GIF, for ``Graphics Interchange Format,'' and Berry et
al. blithely settled on LZW as the compression method. Tim Oren,
Vice President of Future Technology at CompuServe (now with
Electric Communities), wrote: ``The LZW algorithm was incorporated
from an open publication, and without knowledge that Unisys was
pursuing a patent. The patent was brought to our attention, much
to our displeasure, after the GIF spec had been published and
passed into wide use.'' There are claims [1] that Unisys was made
aware of this as early as 1989 and chose to ignore the use in
``pure software''; the documents to substantiate this claim have
apparently been lost. In any case, Unisys for years limited itself
to pursuit of hardware vendors--particularly modem manufacturers
implementing V.42bis in silicon.
All of that changed at the end of 1994. Whether due to
ongoing financial difficulties or as part of the industry-wide
bonk on the head provided by the World Wide Web, Unisys in 1993
began aggressively pursuing commercial vendors of software-only
LZW implementations. CompuServe seems to have been its primary
target at first, culminating in an agreement--quietly announced on
28 December 1994, right in the middle of the Christmas
holidays--to begin collecting royalties from authors of
GIF-supporting software. The spit hit the fan on the Internet the
following week; what was then the comp.graphics newsgroup went
nuts, to use a technical term. As is the way of Usenet, much ire
was directed at CompuServe for making the announcement, and then
at Unisys once the details became a little clearer; but mixed in
with the noise was the genesis of an informal Internet working
group led by Thomas Boutell [2]. Its purpose was not only to
design a replacement for the GIF format, but a successor to it:
better, smaller, more extensible, and FREE.
The Early Days (All Seven of 'Em)
The very first PNG draft--then called ``PBF,'' for Portable
Bitmap Format-- was posted by Tom to comp.graphics,
comp.compression and comp.infosystems.www.providers on Wednesday,
4 January 1995. It had a three-byte signature, chunk numbers
rather than chunk names, maximum pixel depth of 8 bits and no
specified compression method, but even at that stage it had more
in common with today's PNG than with any other existing format.
Within one week, most of the major features of PNG had been
proposed, if not yet accepted: delta-filtering for improved
compression (Scott Elliott); deflate compression (Tom Lane, the
Info-ZIP gang and many others); 24-bit support (many folks); the
PNG name itself (Oliver Fromme); internal CRCs (myself); gamma
chunk (Paul Haeberli) and 48- and 64-bit support (Jonathan
Shekter). The first proto-PNG mailing list was also set up that
week; Tom released the second draft of the specification; and I
posted some test results that showed a 10% improvement in
compression if GIF's LZW method was simply replaced with the
deflate (LZ77) algorithm. Figure 1 is a timeline listing many of
the major events in PNG's history.
indent 4 Jan 95 PBF draft 1 (Thomas Boutell) 4 Jan 95
delta-filtering (Scott Elliott) 4 Jan 95 deflate compression (Tom
Lane et al.) 4 Jan 95 24-bit support (many) 5 Jan 95 TeleGrafix
LZHUF proposal (same or slightly larger) 6 Jan 95 PNG name (Oliver
Fromme) 7 Jan 95 PBF draft 2 (Thomas Boutell) 7 Jan 95 ZIF early
results (Greg Roelofs) 7 Jan 95 internal CRC(s) (Greg Roelofs) 8
Jan 95 gamma chunk (Paul Haeberli) 8 Jan 95 48-, 64-bit support
(Jonathan Shekter) 9 Jan 95 FGF proposal, implementation (Jeremy
Wohl) 10 Jan 95 first NGF/PBF/proto-PNG mailing list (Jeremy Wohl)
15 Jan 95 PBF draft 3 (Thomas Boutell) 16 Jan 95 CompuServe
announces GIF24 development (Tim Oren) 16 Jan 95 spec available on
WWW (Thomas Boutell) 16 Jan 95 PBF draft 4 (Thomas Boutell) 23 Jan
95 PNG draft 5 (Thomas Boutell) 24 Jan 95 PNG draft 6 (Thomas
Boutell) 26 Jan 95 final 8-byte signature (Tom Lane) 1 Feb 95 PNG
draft 7 (Thomas Boutell) 2 Feb 95 Adam7 interlacing scheme (Adam
Costello) 7 Feb 95 CompuServe announces PNG == GIF24 (Tim Oren) 13
Feb 95 PNG draft 8 (Thomas Boutell) 7 Mar 95 PNG draft 9 (Thomas
Boutell) 11 Mar 95 first working PNG viewer (Oliver Fromme) 13 Mar
95 first valid PNG images posted (Glenn Randers-Pehrson) 1 May 95
pnglib 0.6 released (Guy Eric Schalnat) 1 May 95 zlib 0.9 released
(Jean-loup Gailly, Mark Adler) 5 May 95 PNG draft 10 (Thomas
Boutell) 13 Jun 95 PNG home page (Greg Roelofs) 8 Dec 95 PNG spec
0.92 released as W3C Working Draft 23 Feb 96 PNG spec 0.95
released as IETF Internet Draft 28 Mar 96 deflate and zlib
approved as Informational RFCs (IESG) 22 May 96 deflate and zlib
released as Informational RFCs (IETF) 1 Jul 96 PNG spec 1.0
released as W3C Proposed Recommendation 11 Jul 96 PNG spec 1.0
approved as Informational RFC (IESG) 4 Aug 96 VRML 2.0 spec
released with PNG as requirement (VAG) 1 Oct 96 PNG spec 1.0
approved as W3C Recommendation 14 Oct 96 image/png approved (IANA)
indent Figure 1: a PNG timeline
Perhaps equally interesting are some of the proposed
features and design suggestions that ultimately were not accepted:
the Amiga IFF format; uncompressed bitmaps either gzip'd or stored
inside zipfiles; thumbnail images and/or generic multi-image
support; little-endian byte order; Unicode UTF-8 character set for
text; YUV and other lossy image-encoding schemes; and so forth.
Many of these topics produced an amazing amount of discussion--in
fact, the main proponent of the zipfile idea is still making noise
two years later.
Onward, Frigidity
One of the real strengths of the PNG group was its ability
to weigh the pros and cons of various issues in a rational manner
(well, most of the time, anyway), reach some sort of consensus and
then move on to the next issue without prolonging discussion on
``dead'' topics indefinitely. In part this was probably due to the
fact that the group was relatively small, yet possessed of a
sufficiently broad range of graphics and compression expertise
that no one felt unduly ``shut out'' when a decision went against
him. (All of the PNG authors were male. Most of them still are.
I'm sure there's a dissertation in there somewhere...) But equally
important was Tom Boutell, who, as the initiating force behind the
PNG project, held the role of benevolent dictator--much the way
Linus Torvalds does with Linux kernel development. When consensus
was impossible, Tom would make a decision, and that would settle
the matter. (On one or two rare occasions he might later have been
persuaded to reverse the decision, but this generally only
happened if new information came to light.)
In any case, the development model worked: by the beginning
of February 1995, seven drafts had been produced, and the PNG
format was settling down. (The PNG name was adopted in Draft 5.)
The next month was mainly spent working out the details:
chunk-naming conventions, CRC size and placement, choice of filter
types, palette-ordering, specific flavors of transparency and
alpha-channel support, interlace method, etc. CompuServe was
impressed enough by the design that on the 7th of February they
announced support for PNG as the designated successor to GIF,
supplanting what they had initially referred to as the GIF24
development project. [3] By the beginning of March, PNG Draft 9
was released and the specification was officially frozen--just
over two months from its inception. Although further drafts
followed, they merely added clarifications, some recommended
behaviors for encoders and decoders, and a tutorial or two.
Indeed, Glenn Randers-Pehrson has kept some so-called ``paleo
PNGs'' that were created at the time of Draft 9; they are still
readable by any PNG decoder today. [4]
Oy, My Head Hurts
But specifying a format is one thing; implementing it is
quite another. Although the original intent was to create a
"lightweight" format--and, compared to TIFF or even JPEG, PNG is
fairly lightweight--even a completely orthogonal feature set can
introduce substantial complications. For example, consider
progressive display of an image in a web browser. First comes
straight decoding of the compressed data; no problems there. Then
any line-filtering must be inverted to get the actual image data.
Oops, it's an interlaced image: now pixels are appearing here and
there within each 8x8 block, so they must be rendered
appropriately (and possibly buffered). The image also has
transparency and is being overlaid on a background image, adding a
bit more complexity. So far we're not much worse off than we would
be with an interlaced, transparent GIF; the line filters and 2D
interlacing scheme are pretty straightforward extensions to what
programmers have already dealt with. Even adding gamma correction
to the foreground image isn't too much trouble.
But wait, it's not just simple transparency; we have an
alpha channel! And we don't want sparse display--we really like
the replicating progressive method Netscape Navigator uses. Now
things are tricky: each replicated pixel-block has some percentage
of the fat foreground pixel mixed in with complementary amounts of
the background pixels in the block. And just because the current
fat pixel is 65% transparent (or, even worse, completely opaque)
doesn't mean later ones in the same block will be, too: thus we
have to remember all of the original background pixel-values until
their final foreground pixels are composited and overlaid. Toss in
the ability to render all of this nicely on an 8-bit, colormapped
display, and most programmers' heads will explode.
Make It So!
Of course, some of these things are application
(presentation or front-end) issues, not general PNG-decoding
(back-end) issues. Nevertheless, a good PNG library should allow
for the possibility of such applications--which is another way of
saying that it should be general enough not to place undue
restrictions on any programmer who wants to implement such things.
Once Draft 9 was released, many people set about writing PNG
encoders and/or decoders. The true glory is really reserved for
three people, however: Info-ZIP's Jean-loup Gailly and Mark Adler
(both also of gzip fame), who originally wrote Zip's deflate() and
UnZip's inflate() routines and then, for PNG, rewrote them as a
portable library called zlib [5]; and Guy Eric Schalnat of Group
42, who almost single-handedly wrote the libpng reference
implementation (originally ``pnglib'') from scratch. [6] The first
truly usable versions of the libraries were released two months
after Draft 9, on the first of May, 1995. Although both libraries
were missing some features required for full implementation, they
were sufficiently complete to be used in various freeware
applications. (Draft 10 of the specification was released at the
same time, with clarifications resulting from these first
implementations.)
Fast-Forward to the Present
The pace of subsequent developments slowed at that point.
This was partly due to the fact that, after four months of intense
development and dozens of e-mail messages every day, everyone was
burned out; partly because Guy controlled libpng's development and
became busy with other things at work; and partly because of the
perception that PNG was basically ``done.'' The latter point was
emphasized by a CompuServe press release to that effect in
mid-June (and one, I might add, in which their PR guys claimed
much of the credit for PNG's development, sigh).
Nevertheless, progress continued. In June of 1995 I set up
the PNG home page, now grown to roughly a dozen pages [7]; Kevin
Mitchell officially registered the ``PNGf'' Macintosh file ID with
Apple Computer. In August Alexander Lehmann and Willem van Schaik
released a fine pair of additions to the NetPBM image-manipulation
suite, particularly handy under Linux: pnmtopng and pngtopnm
version 2.0. And in December at the Fourth International World
Wide Web Conference, the World Wide Web Consortium (W3C) released
the PNG Specification version 0.92 as an official standards-track
Working Draft.
1996 saw the February release of version 0.95 as an Internet
Draft by the Internet Engineering Task Force (IETF), followed in
July by the Internet Engineering Steering Group's (IESG) approval
of version 1.0 as an official Informational RFC. (However, the
IETF secretary still hasn't issued the actual RFC number at the
time of this writing, five months later. Sigh.) The Virtual
Reality Modeling Language (VRML) Architecture Group in early
August adopted PNG as one of the two required image formats for
minimal VRML 2.0 conformance. [8] Meanwhile the W3C promoted the
spec to Proposed Recommendation status in July and then to full
Recommendation status on the first of October. [9] Finally, in
mid-October the Internet Assigned Numbers Authority (IANA)
formally approved ``image/png'' as an official Internet Media
Type, joining image/gif and image/jpeg as non-experimental image
formats for the Web. Much of this standardization would not have
happened nearly as quickly without the tireless efforts of Tom
Lane and Glenn Randers-Pehrson, who took over editing duties of
the spec from Thomas Boutell.
Current Status
So where are we today? The future is definitely bright for
PNG, and the present isn't looking too bad, either. I now have
over 125 applications listed [10] with PNG support either current
or planned (mostly current); among the ones available for Linux
are:
+ XV (image viewer/converter)
+ ImageMagick (image viewer/converter)
+ GRAV (image viewer)
+ Zgv (image viewer)
+ xli (image viewer)
+ XPaint (image editor)
+ The GIMP (image editor)
+ Image Alchemy (image converter)
+ pnmtopng/pngtopnm (image converters)
+ XEmacs (editor/web browser/operating system/etc.)
+ gforge (fractal terrain generator)
+ Fractint (fractal generator)
+ Ghostscript (PostScript viewer/converter)
+ GNUplot (plotting program)
+ PV-WAVE (scientific visualization program)
+ POV-Ray (ray-tracer)
+ VRweb (VRML browser)
+ X Mosaic (web browser)
+ Arena (web browser)
+ Chimera (web browser)
+ Grail (web browser)
+ Amaya (web browser/editor)
+ Mapedit (image-map editor)
+ WWWis (HTML IMG sizer)
+ file(1) (Unix file-type identifier)
Discerning readers will note the conspicuous absence of
Netscape Navigator. Despite the fact that Netscape was aware of
the PNG project from the beginning and unofficially indicated
``probable support''; despite the nice benefits gamma correction,
alpha support and 2D interlacing bring to WWW applications;
despite the fact that the WWW Consortium, of which Netscape is a
member, released the PNG spec as its first official
Recommendation; despite the requirement to support PNG in VRML 2.0
viewers like Netscape's own Live3D plug-in; and despite
considerable pestering by members of the PNG group and the
Internet community at large, Netscape is still only
``considering'' future support of PNG. Until Netscape either
supports PNG natively or gets swept away by Microsoft or someone
else, PNG's usefulness as an image format for the Web is
considerably diminished.
On the other hand, our buds at Microsoft recognized the
benefits of PNG and apparently embraced it wholeheartedly. They
have not only made it the native image format of the Office97
application suite but have also repeatedly promised to put it into
Internet Explorer (theoretically by the time of the 4.0
betas--we'll see about that). Assuming they do, Netscape is almost
certain to follow suit. (See? Microsoft is good for something!) At
that point PNG should enjoy a real burst of WWW interest and
usage.
In the meantime, PNG viewing actually is possible with Linux
Netscape; it's just not very useful. Rasca Gmelch is working on a
Unix plug-in with (among other things) PNG support. Although it's
still an alpha version and requires ImageMagick's convert utility
to function, that's not the problem; Netscape's brain-damaged
plug-in architecture is. Plug-ins have no effect on HTML's IMG
tag: if there's no native support for the image format and no
helper app defined, the image is ignored regardless of whether an
installed plug-in supports it. Instead you must use Netscape's
EMBED extension. That means anyone who wants universally viewable
web pages loses either way: PNG with IMG doesn't work under
Netscape, and PNG with EMBED doesn't work under much of anything
except Netscape and MSIE (and those only if the user has installed
a working PNG plug-in).
But support by five or six other Linux web browsers ain't
bad, and even mainstream applications like Adobe's Photoshop now
do PNG natively. More are showing up every week, too. Life is
good.
The Future
As VRML takes off--which it almost certainly will,
especially with the advent of truly cheap, high-performance 3D
accelerators--PNG will go along for the ride. (JPEG, which is the
other required VRML 2.0 image format, doesn't support
transparency.) Graphic artists will use PNG as an intermediate
format because of its lossless 24-bit (and up) compression and as
a final format because of its ability to store gamma and
chromaticity information for platform-independence. Once the
``big-name'' browsers support PNG natively, users will adopt it as
well--for the 2D interlacing method, the cross-platform gamma
correction, and the ability to make anti-aliased balls, buttons,
text and other graphic elements that look good on *any* color
background (no more ``ghosting,'' thanks to the alpha-channel
support).
Indeed, the only open issue is support for animations and
other multi-image applications. In retrospect, the principal
failure of the PNG group was its delay in extending PNG to MNG,
the "Multi-image Network Graphics" format. As noted earlier,
everyone was pretty burned out by May 1995; in fact, it was a full
year before serious discussion of MNG resumed. As (bad) luck would
have it, October 1995 is when the first Netscape 2.0 betas arrived
with animation support, giving the (dying?) GIF format a huge
resurgence in popularity.
At the time of this writing (mid-December 1996), the MNG
specification has undergone some 27 drafts--almost entirely
written by Glenn Randers-Pehrson--and is close to being frozen. A
couple of special-purpose MNG implementations have been written,
as well. But MNG is too late for the VRML 2.0 spec, and despite
some very compelling features, it may never be perceived as
anything more than PNG's response to GIF animations. Time will
tell.
At Last...
It's always difficult for an insider to render judgment on a
project like PNG; that old forest-versus-trees thing tends to get
in the way of objectivity. But it seems to me that the PNG story,
like that of Linux, represents the best of the Internet:
international cooperation, rapid development and the production of
a Good Thing that is not only useful but also freely available for
everyone to enjoy.
Then again, maybe I'm just a shameless egotist (nyuk nyuk
nyuk). You decide....
Acknowledgments
I'd like to thank Jean-loup Gailly for his excellent
comp.compression FAQ, which was the source for much of the patent
information given above. [11] Thanks also to Mark Adler and JPL,
who have been the fine and generous hosts for the PNG home pages,
zlib home pages, Info-ZIP home pages and my own, personal home
pages. (Through no fault of Mark's, that will all come to an end
as of the new year; oddly enough, JPL has decided that none of it
is particularly relevant to planetary research. Go figure.)
References [1] Raymond Gardner, rgardner@teal.csn.org, 8 Jan 1995
23:11:58 GMT, comp.graphics/comp.compression, Message-ID . See
also Michael Battilana's article discussing the legal history of
the GIF/LZW controversy:
http://www.cloanto.com/users/mcb/19950127giflzw.html [2]
http://www.boutell.com/boutell/ [3]
http://www.w3.org/pub/WWW/Graphics/PNG/CS-950214.html [4]
http://www.rpi.edu/~randeg/paleo_pngs.html [5]
http://quest.jpl.nasa.gov/zlib/ [6]
ftp://swrinde.nde.swri.edu/pub/png/src/ [7]
http://quest.jpl.nasa.gov/PNG/ (but probably moved to
http://www.wco.com/~png/ by 1 January 1997) [8]
http://vag.vrml.org/VRML2.0/FINAL/spec/part1/conformance.html
[9] http://www.w3.org/pub/WWW/TR/REC-png.html [10]
http://quest.jpl.nasa.gov/PNG/pngapps.html [11]
http://www.cis.ohio-state.edu/hypertext/faq/usenet/compression-f
aq/top.html indent &copy 1996 by Michael J. Hammel
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
INDEXING TEXTS WITH SMART
By Hans Paijmans paai@kub.nl
_____________________________________________________________
1. The uses of Linux and MS-DOS
Although my colleagues here on Tilburg University may think that I
spend my time fiddling with Linux on a PC that could be put to
better uses, they are wrong. The 'fiddling with Linux' I do at
home; at my work I only do the bare minimum necessary to keep
Linux fed and happy. As most readers of this journal know, this
involves making the occasional backup and for the rest: nothing.
When I sit in front of my PC, I work (well, mostly). Linux makes
it possible to do my work with a minimum of fuss and a big part of
the credit for this goes to Jacques Gelinas, the man who wrote
Umsdos: a layer between the Unix operating system and the vanilla
MS-DOS 8+3 FAT system. This makes it possible to access the
DOS-partition of my hard disk from either operating system. This
is good news, because I am totally dependent from two programs:
SMART, an indexing and retrieval system and SPSS for Windows to
twiddle the data I obtain form SMART. SMART only runs under Unix
(and not all Unixes for that matter) and SPSS4Windows, obviously,
runs under MS-Windows and whatever the virtues of this operating
system may be, you emphatically do not want to use it in any kind
of experimental environment.
I suppose that SPSS (Statistical Package for the Social Sciences)
will be familiar to most Linux users. If not: SPSS is just what it
says, a statistical package but not only for the 'social sciences'
but for about everyone who needs statistical analysis of his data.
SMART, however, is an indexing and retrieval program for text.
What is more: it does not just index the words, it also adds
weights to them. It also allows the user to compare the indexed
documents in the so-called Vector Space Model and to compute the
distances between the documents, or between documents and queries.
To understand why this is special we must delve a bit in the
typical problems of Information Retrieval, i.e. the storage of
books, articles etcetera and the retrieval of those on content.
1.1 Why indexing is not enough
When at the end of the sixties automatic indexing of texts became
a viable option many people thought that the problems of
information retrieval were solved. Programs like STAIRS (IBM,1972)
enabled the users to file and rapidly retrieve documents on any
word in the text or on boolean combinations (AND, OR, NOT) of
those words and who could ask for more? Then, in 1985 a famous
article was published by two researchers in the field [1]. In this
article they reported on the performance of STAIRS in real life
and they showed that the efficiency of STAIRS and similar systems
was, in fact, much lower than assumed. Even experienced users
could not obtain a recall of more than 20-40% of the relevant
documents in a database of 100,000 documents, and worse, they were
not aware of the fact.
The problem with all retrieval systems of this type is that human
language is so fuzzy. There may be as much as a dozen different
terms and words pointing to one and the same object, whereas one
word may have widely different meanings. In Information Retrieval
this will lead to one of two situations. Either you try to obtain
a high precision, when almost all the retrieved documents are
relevant (but an unknown number of other relevant documents are
not included) or you go for high recall, but then a lot of
irrelevant documents will be included in the result. When in a
retrieved set of documents the proportion of irrelevant documents
is high, the user will probably stop looking at the documents
before he or she has found all the relevant ones: in fact his
futility-point has been reached. In such a case the net result
is equal to the situation in which those relevant records that
would be presented after the user reached that futility-point were
not retrieved. Therefore the concept of ranking, i.e. the ordering
of retrieved documents on relevance, is very important in
Information Retrieval.
2. SMART
Modern (and not so modern) research has offered a number of
possible solutions to this dilemma. Some of those solutions use
the concept of weighted keywords. This means that every
keyword-document combination has a weight attached that
(hopefully) is an indication of the relevance of that particular
keyword for that particular document. SMART does just that: it
creates indexes for a database of documents and attaches weights
to them. The way that happens may be expressed intuitively as 'the
more a word occurs in the less documents, the higher the weight'.
Or, if the word 'dog' occurs twenty times in a given document, but
in no other documents, you may be relatively certain that this
document is about dogs. Information Retrieval addicts like me talk
about the tf.idf weight.
Smart offers several options as to how that weight should be
arrived at: I generally prefer the so-called atc-variation,
because it adjusts for the length of the individual documents.
It calculates the tf.idf in three steps. The first step creates
the value tex2html_wrap_inline96 for the term-frequency (tf) as
displaymath86
where tex2html_wrap_inline100 is the term with the highest
frequency in the document. This adjusts for the document-length
and the number of terms. Then the weight tex2html_wrap_inline102
is calculated as
displaymath87
where N is as before the number of documents and F the document
frequency of term t (the number of documents in which term t
occurs). Finally the cosine normalization is applied by
displaymath88
where T is the number of terms in the document vector. Now we have
a number between zero and one that hopefully correlates with the
importance of the word as a keyword for that document. For a
detailed discussion of these and similar techniques see e.g.
Salton and McGill ([2]). You will love it!
This is not all. When SMART has constructed the index in one of
the various ways available, it also can retrieve the documents for
you. This is done according to something called ``the Vector Space
Model''. This model is best explained using a three-dimensional
example of a vector-space; you can add another few thousand
dimensions in your own imagination.
Imagine you want to index your documents according to three
keywords 'cat', 'dog' and 'horse'; keywords that may or may not
occur in your documents. So you draw three axes to get a normal
three-dimensional coordinate system. One dimension can be used to
indicate the ``cat-ness'' of every document, the other its
``dog-ness'' and the third the ``lion-ness''. To make things easy
we only use binary values 0 and 1, although SMART can cope with
floats (the 'weights' mentioned before. So if a document is about
cats, it scores a one on the corresponding axis, otherwise it
scores a zero. Any document may now be drawn in that space
according to the occurrence of one or more of the keywords and now
we have a relatively easy way to compute the difference between
those document. Moreover a query consisting of one or more of the
keywords can be drawn in the same space and the documents can be
ranked according to the distance to that query. Of course a
typical document database has thousands of keywords and
accordingly thousands of dimensions, but the arithmetics involved
in multi-dimensional distances do not matter much to modern
computers, and if they bother you, you just have to smoke
something illegal and matters will rapidly become clear. If only
till the next morning.
So SMART accepts queries, ranks the documents according to the
``nearness'' to that query and return them to you in that order.
Therefore it is still one of the best retrieval systems that are
ever written although it lacks the bells and whistles of its more
expensive counterparts in some operating systems I could mention.
And although it is not really optimized for speed, it runs
typically 10-30 times faster than the fastest indexing program I
ever saw under MS-Windows.
3. The DOS connection
But I am not using SMART for bread-and-butter retrieval, but for
the weights it computes and the indexes it creates. At this point
I want to do some other manipulations of these data and again I
have to offer my thanks to the developers of unix in general and
to Linux in particular. A whole string of ever more complicated
and sophisticated shell scripts, the standard unix tools and a few
of My Very Own utilities suffice to process the SMART output to a
file that is ready for importing in SPSS.
Nevertheless now I have to quit Linux and boot MS-DOS, start
MS-Windows and finally enter SPSS to do the statistics and create
some graphs. I am a newcomer to Unix (indeed it was the fact that
Linux offered a way to use SMART that pulled me over the line two
years ago), but already I am wondering how people can live in the
stifling atmosphere of MS-Windows. The fact that you can't really
run two applications at the same time is not even the worst thing.
But who is responsible for the idea that Icons and Popups were
better and more efficient than the plain old command line? And
what happened to pipes and filters? And a sensible command
language? Be that as it may, SPSS gets the job done and when the
output is written to disk I immediately escape back to Linux to
write the final article, report or whatever with LaTeX.
4. The bad news
On this point I have two messages: one is good, the other bad.
I'll start with the good news. SMART is obtainable by anonymous
ftp from Cornell University and may be used for free for
scientific and experimental purposes. Better yet: it compiles
under Linux without much tweaking and twiddling. Also there exists
a fairly active mailing list for people who use SMART
(smart-peoplecs.cornell.edu).
The bad news: the manual. What manual? SMART is not for the faint
of heart; after unpacking and compilation you'll find some
extremely obscure notes and examples and that is it. Nevertheless,
if you have more than just a few megabytes of text to manage AND
the stamina to learn SMART, it certainly is the best solution for
your information retrieval needs. But don't I wish somebody would
write a comprehensive manual! In the meantime you may perhaps be
helped by my ``tutorial for newbees'', to be found at
http://pi0959.kub.nl:2080/Paai/Onderw/Smart/hands.html.
_____________________________________________________________
BIBLIOGRAPHY
1
Blair, D.C.; Maron, M.E.,An evaluation of retrieval effectiveness
for a full-text document retrieval system,Communications of the
ACM V28:3, 1985, pp. 289-299.
2
G. Salton and M.J. McGill,Introduction to Modern Information
Retrieval New York [etc.] : McGraw-Hill, 1983.
_____________________________________________________________
Copyright &copy; 1997, Hans Paijmans
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Back Next
_____________________________________________________________
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
About Linux text editors / product announcement
By Oleg L. Machulskiy machulsk@shade.msu.ru
_____________________________________________________________
+ Generally about Linux text editors
+ What I'd like to have in text editor
+ Some program examples
_____________________________________________________________
Generally about UNIX text editors
All of my friends who use Linux always told me that text editors
is very important problem under this OS (I mean text-mode editors
with 100K executable for writing programs). As I understand, this
problem is not a problem of Linux itself, but it's a problem of
every UNIX. What's more I know which reasons cause this trouble.
There is two reasons: putc output to screen and getc input from
keyboard. In other OS-es user (programmer) can catch Alt+<letter>
or Shift+<letter> keystrokes and use it as a commands of editor.
In UNIX user has only 256 ASCII-codes avialable (really, much less
than 256) and because of it every UNIX editor uses either very
long sequences of keystrokes as editing commands (as emacs or joe)
or it has two editing modes (command mode and typing mode in VI
for example). On X-s everything is better, because here we can get
scan code (not real scan, but this code is anough for all my
needs) of the key pressed and status of Shift-keys (Alt, Caps,
Shift, Ctrl and mouse buttons), so we can use functional keys,
arrow-keys and everything else You can find on Your keyboard
(everybody knows how to do that).
But even with text mode editors under Linux everything is not so
bad: You can switch keyboard to RAW mode and do with it all You
want (don't forget to get another console from which You will
execute shutdown -r now command during beta-testing Your program).
But it's very important to understand that RAW-keyboard programs
will not work through telnet. Also is very important to set
SIGSEGV and SIGKILL signal handlers so that they'll switch
keyboard back to normal mode from RAW when something happens. Once
I heard about kernel patching so that You can use ScrollLock key
to switch between raw and normal mode, but I don't know how to
apply this patch.
_____________________________________________________________
What I'd like to have in text editor
Caution : This section is very private. Maybe someone will find
something useful for him(here) here, but probably not. This
section is mostly about my own text editor, so, if You got used to
Turbo-Vision-like editors and You're satisfied, then probably You
will find the follwing not interesting. So don't read it, don't
waste Your time.
Editor must be the same on every operating system
(multi-platform).
Editor must handle advanced search feature: I need not only case
sensetive/insensetive search, but as a minimum a wildcard
searh or regular expressions search (this type of search
includes wildcards).
Editor must support projects: user must be able to create a list
of files (sources of some program) and walk through these
files freely (enter into file, quit from file, switch to
another file, ...). The possible solution is to assign some
keystroke as an "enter-into-file" command, and then, when
user invokes "enter-into-file", open a file with a name
similar to the word under cursor (For example, you can enter
in h-file from the text of c-program; just move cursor to the
#include "..." statement and press the "enter-into-file"
key).
Editor must handle many files opened at the same time so that
user can freely move from one text to another (very often I
need to read declarations of functions in .h files)
Editor must support compiling, make etc. from within text editor
(generally: execution OS command from within editor)
Commands must be rather simultaneous pressings of a few keys
than sequences of keystrokes. It seems to me, it isn't
comfortable to type (F10, 'F', 'O' , filename) every time You
need to open a new file. Besides, with such a keyboard layout
it's impossible to work fast. This requirement causes a
problem: text editor cannot work through telnet, because
telnet protocol transfers only ASCII-codes, but not
scan-codes.
Text editor must consider a text not as a sequence of chars but
as a sequence of lines, where each line is a sequence of
chars. There is a lot of text editors in which text is a
vector (For example ME (MSDOS MultiEdit) , Turbo Editor
(Borland Programming Environments), JOE (linux), etc.), But I
don't know how to work with tables in these editors or how to
set // (C++ comment) at the beginning of 10 lines of program
on the screen.
Editor must support macrocommands as a recordable sequences of
keystrokes.
If editor supports programming language, so that I can write my
own commands, it would be fine.
I think programs-structurizing is very useful feature. I'll
explain: I'd like to have text of my program in pre-hypertext
form so that I see a list of functions on the screen, I put
cursor on the name of desired function, press "open"-key and
now I can edit source of that function, but besides that I
must be able to edit this file with usual text editor and I
must be able to compile that file without errors, hence all
additional info about hypertext structure of program must be
placed into comments (comments are specific for each file
type, but in most cases it depends on file extension).
Keyboard layout must be as much tunable as possible (if my End
key is broken, I can use F11 key instead). Besides I often
need keyboard layout for second language (cyrillic).
I don't like when editor wastes screen space on frames of
windows or any other unuseful things (80 * 25 isn't very
roomy)
Font on the screen must be fixed (I hate proportional fonts).
If You're interested in all that, You can try our example of such
a text editor. I think it isn't the best editor, but I got used to
it. May It will be useful for someone. To get it, go to
http://shade.msu.ru/~machulsk and download 330K zip file, which
contains sources and 5 executables for Linux console, Linux X11,
OS/2, DOS and Win32 (95/nt). Docs are also included in HTML /
plainTeX format.
_____________________________________________________________
Example of switching to RAW keyboard mode (C++ syntax)
#include <stdio.h > #include <stdlib.h > #include <unistd.h > #include
<errno.h > #include <linux/kd.h > #include <signal.h > #include <sys/ioc
tl.h > /*.................*/
void Terminate(int a) {
if( ioctl(con_fd,KDSKBMODE,om)<0 ) {puts("Press RESET?");exit(-1);}
/*trying to set old keydoard mode*/
}
/*.................*/
class TKeyboard{
int om; /* old keyboard mode descriptor */
int con_fd; /* console descriptor */
TKeyboard(){
signal(SIGKILL, Terminate ); /*setting SIGKILL signal handler*/
signal(SIGQUIT, Terminate ); /*setting SIGQUIT signal handler*/
signal(SIGSEGV, Terminate ); /*setting SIGSEGV signal handler*/
if( 0==(con_fd=open("/dev/tty",O_RDWR)) ) {puts("error");exit(-1);}
/*getting console descriptor*/
if( ioctl(con_fd,KDGKBMODE,&om)<0 ) {puts("error");exit(-1);}
/*getting old keydoard mode*/
if( ioctl(con_fd,KDSKBMODE,K_RAW)<0 ) {puts("error");exit(-1);}
/*setting RAW keydoard mode*/
}
~TKeyboard(){
Terminate(0);
}
int GetScanCode(){
int c;
ioctl(con_fd,TIOCINQ,&cd); /*query*/
if(cd==0) /*keyboard buffer is empty*/
read(con_fd,&c,1); /*get next scancode from console*/
}
} KBD;
/*.................*/
void main() {
/*.................*/
/*................. program body */
/*.................*/
}
_____________________________________________________________
Thank You!
My addresses: machulsk@shade.msu.ru
homepage on(in?) Shade
_____________________________________________________________
scuze me for bad english, but my native language is Russian
_____________________________________________________________
Copyright &copy; 1997, Oleg L. Machulskiy
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Back Next
_____________________________________________________________
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
TWO NEW X-WINDOWS MAIL CLIENTS
by Larry Ayers
Copyright (c) 1996
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
INTRODUCTION
There are several full-featured text-mode mail clients available
for Linux, and these programs (such as Pine and Elm) are probably
the most commonly used mailers in the Linux/unix world. One reason
for this tendency is that they run equally well in both console
and X sessions (in an xterm). They also have a longer development
history than their X-windows counterparts which results in the
accretion of more features and options. There has been ample time
for the developers to deal with bugs as well.
Many of the X-windows mailers I've tried have either been too
basic, too beta, or awkward to use. I've always returned to Pine,
my standby. Recently two X-based mailers have been released (in
late beta versions), both of which are stable and well-provided
with features and options. When I say stable I mean that they have
functioned well for me, I haven't lost any mail, and they both
have been through several releases in which the most egregious
bugs seem to have been ironed out.
Mail programs are a rather personal sort of software. I've found
it to be prudent to copy any existing mailbox files or directories
to a safe location before installing any new mail client. You
never know until you try just what a new mailer will do with your
existing mail messages the first time it is run. As an example,
mbox-style mail "folders" (which are just single files with
messages concatenated) might be willy-nilly transformed into
MH-style directories, with each message becoming an individual
numbered file. I suppose there may exist a technique to reverse
this metamorphosis, but I don't know what it might be, aside from
manually using an editor.
_____________________________________________________________
TKMAIL
Paul Raines has been working on a Tcl/Tk mail client for some time
now. I'll let him describe its origin:
I began the project at the beginning of '92 while a physics
grad student at the Univ. of Penn. I had been put in charge
of several SGI workstations and was disappointed in the X
window mail readers I had found. I had recently got into
Tcl/Tk programming and played around with putting Tk
interfaces on top of command line programs for physics
simulation. I figured it would be easy to do one to sit on
top of the mailx command and did. That produced tkmail 1.x.
Eventually I decided I was too limited by the mailx command
and wrote a Perl backend to serve as an extensible
equivalent. That produced tkmail 2.x. Perl was used because
its text processing features were much faster than Tcl but I
wanted to keep the whole program as scripts for portability.
This proved a lost cause as Perl proved as hard to port as C
code. For my update to work with Tk4.0, I decided to drop
Perl in favor of writing my own C code as a module extension
to Tcl. The past year was the last of my graduate career and
mostly devoted to finishing my thesis leaving little time
for work on tkmail. It is sort of behind in some of the
features out there today (MIME, POP, IMAP, etc) but I hope
to rectify that soon.
The most important future plans are:
* better MIME support
* better key binding customization
* an "auto-filing" feature
* better search support
TkMail is very customizable; Paul Raines includes with the
distribution an alternate Tk text-manipulation library which
allows the use of emacs-style key-bindings in the compose window.
This library can be used with other Tk programs as well. Colors
and fonts can be independently selected for the folder-view and
compose window. Much of the configuration can be done from
menu-selections.
Here is a screenshot of the main folder-view window:
Tkmail Main Window
And here is one of the composition window:
the Composition Window
TkMail, like many other Linux mailers, in effect acts as a
front-end to sendmail. Luckily most recent Linux distributions
come with sendmail preconfigured. If your inbox is on a POP server
you will need to use popclient, fetchmail, or fetchpop to retrieve
your messages and leave them in a mailbox file on your local disk,
where mail clients can find them.
Among the many features of this beta release are:
+ easy inclusion of files into message compositions with
automatic uuencoding and compression, if desired
+ ability to access an alternate editor from the composition
window
+ spell check compositions using an X windows interface (using
ispell)
+ reads aliases from either standard .mailrc or elm aliases.txt
+ sorting of messages on any field and the ability to write out
the folder physically in that order
+ simple MIME reading and composition tool
+ built in 'biff' icon for notification of new mail on multiple
folders
+ dynamic (at startup) menus for quick access to mail folders
for reading, copying, and moving messages
TkMail is set up initially to open a small debugging window from
which the main program can be started. Once it becomes evident
that the program is working to your satisfaction this can be
disabled by editing the main tkmail4 script and changing the line
set mfp(debug) 1 to set mfp(debug) 0, or just start it with the
-nodebug option.
I have found TkMail 4.0b8 to be easy to learn and use, and its
interface is nice-looking. With a little more work on the MIME
abilities it will be as effective an X mail client as any
available.
Paul Raines maintains a home page for TkMail; the source for the
4.0b8 version is available here.
_____________________________________________________________
XFMAIL
Some months ago John Fisk wrote about the XFmail program in the
Gazette. His account inspired me to try it out, but I had quite a
few problems with the message editing window, so much so that when
I tried to mail the developers a comment on their program, the
message was corrupted and I doubt that it was legible to them. I
gave up and deleted it soon after, making a mental note to check
it out later when perhaps it had become more usable.
Recently I did just that, and found that a new editing module had
been contributed which really makes a difference in usage of the
mailer. No longer is there a limit to the amount of the text in
the editing window. This change, I believe, makes XFMail a
credible choice as a Linux mail client.
XFMail requires the XForms library. This is available from the
XForms web-site, which will always have the latest version and
news. If you obtain the archive be aware that the package includes
a GUI designer as well as many samples. All you need to keep if
you're not a programmer is the XForms shared and static libraries
(libforms.so.81 and libforms.a) and the header file (forms.h).
These three files will enable you to compile XForms applications,
such as XFMail from source.
In order to try the current beta (which I recommend) you'll need
to obtain the source archive from the XFMail home FTP site. As
long as you have the XForms library files installed it should
compile for you, notwithstanding the warning message at the FTP
site. If your current mailbox is in the common mailx format (a
single file), you might want to copy the file (INBOX or whatever)
to another location before installing XFMail. The default
behaviour is for XFMail to transform your messages into the
multiple-file MH format; after installation you can disable this
and move your mailbox back. If you already store your mail in the
MH manner the program will load your messages without moving them.
Even though XFMail reads and stores messages in MH format, it
doesn't require that you have the MH system installed.
This mail client can handle all mail fetching and delivery needs
for a single-user machine. The user is given the option of using
sendmail for delivery (either on- or off-line), or using XFMail to
directly contact the SMPT server and deliver outgoing mail.
Fetching new mail can be done externally,(popclient et al), or via
XFMail directly. These features could be helpful for new users who
would rather not deal with sendmail; all functions can be handled
by the mailer.
XFMail has the recognizable XForms look, familiar to users of the
Lyx front-end program for TeX/Latex. The XForms library gives
programs a unique look, unlike standard X or Motif. The user
interface is perhaps not quite as fancy as some, but it's not hard
to become accustomed to it. There are some limitations in choice
of colors; the selection available is greater than that of
console-ANSI programs, but less than the amount available to
standard X clients.
Here are some screenshots of the various XFMail windows:
The Main Window
The Composition Window
And here is the logging window:
[IMAGE]
Among the other features of this mailer are an internal address
book, full MIME support, and support for faces and picons. Support
is planned for compatibility with mailx-style mail-folders.
XFMail is quite an ambitious programming project; if you do try
out the beta version I'm sure the authors would appreciate hearing
any comments you may have. There also exists an XFMail mailing
list; send a message to: majordomo@Burka.NetVision.net.il with
"subscribe xfmail" in the message body.
Visit the XFMail homepage for the latest news; by the time you
read this, beta 0.5 may well have been released.
XFMail is being developed by Gennady B. Sorokopud and Ugen J.S.
Antsilevich.
_____________________________________________________________
Larry Ayers<layers@vax2.rainis.net>
Last modified: Tue Dec 17 19:05:43 CST 1996
_____________________________________________________________
Copyright &copy; 1997, Larry Ayers
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Back Next
_____________________________________________________________
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
MISCELLANEOUS NOTES
by Larry Ayers
Copyright (c) 1996
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
FUN WITH LITTLE SHELL-SCRIPTS
After typing the same command or editing the same rc-file for the
dozenth time the idea of a short executable shell-script will
gradually rise to the surface of my mind. As an example, last year
after much trial-and error I figured out how to start my S3
X-server in 16-bit mode. This was great, but I found that there
were a few programs which preferred to be run in 8-bit mode.
Typing startx -- -bpp 16 and startx -- -bpp 8 began to become
tiresome; then it dawned on me that I could write a shell script
for each color-depth which would do the typing for me. One of them
looks like this:
#!/bin/sh
# x16: starts x in 16-bit mode
startx -- -bpp 16
Just a simple little script (made executable with chmod +x x16)
but so handy!
Encouraged by this, it occurred to me that changing
window-managers could be done in a similar way. I normally use
fvwm2, but lately I've been fooling around with one of fvwm's
hacked offspring, the Afterstep window-manager. Since I didn't
have Afterstep's configuration quite as usefully customised as my
mainstay fvwm2's, I didn't want to use it the majority of the
time. Rather than editing ~/.xinitrc each time I wanted to switch
to Afterstep, then again to switch back, I copied ~/.xinitrc
twice. The first copy is .xinitrc-f and it's just my normal copy.
The second, .xinitrc-a starts Afterstep instead. The scripts which
control this are as follows:
#!/bin/sh
# xa: starts x with afterstep
cp ~/.xinitrc-a ~/.xinitrc ; startx
and
#!/bin/sh
# xf: starts x with fvwm2
cp ~/.xinitrc-f ~/.xinitrc ; startx
Of course, while in an X-session another window-manager can be
easily started from a menu. I spend a fair amount of time working
in a console session without X running, in which case the above
scripts are useful.
It just occurred to me as I write this that these tasks could be
as easily done using aliases or functions in ~/.bashrc. The only
difference I suppose would be that shell-functions are
memory-resident whereas the scripts aren't.
These examples may seem self-evident or trivial to the unix-gurus
out there, but they were part of the learning process for me.
Perhaps this piece will encourage the beginners out there to try
some similar scripting.
_____________________________________________________________
KEYBOARDS AND RXVT
Here's a discovery I made recently concerning rxvt, the
memory-saving alternative to xterm. I received an email message
recently in response to my article last month concerning S-lang
applications, in which I opinionated about rxvt vs. xterm. The
poster of the message wondered whether there is any way to use
shift-page-up and shift-page-down to scroll the rxvt window,
similar to the way console screens (and xterms) scroll. I had
tried to get this to work without success, and some usenet
messages had led me to believe that without patching the source
rxvt just wouldn't scroll from the keyboard.
Recently I installed the S.u.S.E. distribution, but didn't install
the supplied rxvt package. I recompiled rxvt version 2.19 in this
new environment, and to my surprise the above-mentioned scrolling
keys worked! This piqued my curiosity, so I began prowling through
the directory hierarchy searching for the difference in config
files which made this behaviour possible. I came up with two
differences: first, there was a new entry in the ~/.Xmodmap file.
The lines
keycode 64 = Meta_L
keycode 0x6D = Multi_key
had been added to the "keycode 22 = BackSpace" line which I had in
my previous installation. Second, the /etc/termcap file was
different than the ones I'd seen before; a new rxvt stanza had
been included which looks like this:
rxvt|rxvt terminal emulator:\
:am:km:mi:ms:xn:xo:\
:co#80:it#8:li#65:\
:AL=\E[%dL:DC=\E[%dP:DL=\E[%dM:DO=\E[%dB:IC=\E[%d@:\
:LE=\E[%dD:RI=\E[%dC:UP=\E[%dA:ae=^O:al=\E[L:as=^N:bl=^G:\
:cd=\E[J:ce=\E[K:cl=\E[H\E[2J:cm=\E[%i%d;%dH:cr=^M:\
:cs=\E[%i%d;%dr:ct=\E[3k:dc=\E[P:dl=\E[M:do=^J:ei=\E[4l:\
:ho=\E[H:ic=\E[@:im=\E[4h:\
:is=\E[r\E[m\E[2J\E[H\E[?7h\E[?1;3;4;6l\E[4l:\
:k1=\E[11~:k2=\E[12~:k3=\E[13~:k4=\E[14~:k5=\E[15~:\
:k6=\E[17~:k7=\E[18~:k8=\E[19~:k9=\E[20~:kI=\E[2~:\
:kN=\E[6~:kP=\E[5~:kb=\177:kd=\EOB:ke=\E[?1l\E>:kh=\E[H:\
:kl=\EOD:kr=\EOC:ks=\E[?1h\E=:ku=\EOA:le=^H:md=\E[1m:\
:me=\E[m:mr=\E[7m:nd=\E[C:rc=\E8:sc=\E7:se=\E[m:sf=^J:\
:so=\E[7m:sr=\EM:ta=^I:te=\E[2J\E[?47l\E8:ti=\E7\E[?47h:\
:ue=\E[m:up=\E[A:us=\E[4m:
I have noticed, though, that if I type the command echo $TERM in
an rxvt window the result is xterm-color, so perhaps the above
rxvt termcap entry isn't being used at all.
I'd love to know if anyone else has any luck transplanting either
or both of these two changes into their system. The rxvt termcap
entry can be pasted right into your /etc/termcap file; in mine it
is right after the xterm stanzas. I don't believe the order of
stanzas is important, though.
_____________________________________________________________
PARTITIONS AND DIRECTORIES
After using linux for a while you tend to take for granted the
supple flexibility inherent in the Linux manner of dealing with
files, partitions, and mount-points. Recently I began to feel
constrained by a relatively small /usr partition, so I thought I'd
do some experimenting.
I happened to have an unused 100 mb. partition on my disk, so I
created an ext-2 filesystem on it and mounted it on an empty
directory, /new, created for this purpose. Then I ran this
command: cp -a /usr/X11R6 /new. Using cp with the -a switch is
really handy, as it copies all subdirectories, links, and files,
and also saves permissions.
The next step was modifying the /etc/fstab file, inserting the
following entry which causes /usr/X11R6 to be mounted on the new
partition:
/dev/hda11 /usr/X11R6 ext2 defaults 1 2
Before rebooting I dropped back to a console and deleted the
entire contents of the /usr/X11R6 directory.
I was reasonably certain this would work, but I must confess I was
surprised when (after rebooting) X started up without comment, as
if nothing had changed.
Linux doesn't really care, after all, where files are located, as
long as there is a congruence between the partition table and the
contents of the /etc/fstab file. One benefit of this laxity is
that repartitioning (with all of the attendant backing up,
restoring, etc.) should seldom be necessary.
_____________________________________________________________
Larry Ayers<layers@vax2.rainis.net>
Last modified: Tue Dec 17 21:31:27 CST 1996
_____________________________________________________________
Copyright &copy; 1997, Larry Ayers
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Back Next
_____________________________________________________________
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
Petition to Cancel Filed Against Linux Trademark
Members of the LINUX community have been up in arms during the
past six months over the efforts of an individual named William R.
Della Croce, Jr. from the Boston area to collect 10% royalties on
sales from businesses marketing Linux products. He bases his
written demands on a US trademark which he claims to hold on the
name "LINUX" for a computer operating system. He, in fact, holds
such a registered trademark, based on his claim made under penalty
of perjury that he is the owner and first user of the mark for
operating systems, and that he was not aware in 1994 or 1995 of
any other person who might claim or be using this name and mark
for an operating system. This claim is absurd on its face.
WorkGroup Solutions, Yggdrasil Computing, Linux International,
SSC/Linux Journal, and Linus Torvalds have retained an
internationally known software industry attorney, G. Gervaise
Davis III, of the Davis & Schroeder law firm in Monterey, CA to
seek cancelation of this registration on the grounds that it is
fraudulent and obtained under false pretenses. Mr. Davis and his
firm are handling the case on a vastly reduced fee basis, because
of their long standing relationship with the U.S. software
industry. Davis was the original attorney for Gary Kildall and
Digital Research of CP/M fame in the 1980s.
A Petition to Cancel was in fact filed with the Trademark Trial
and Appeals Board in Washington, DC. on November 27, 1996,
detailing the improper actions of Della Croce and setting out the
true facts with a number of exhibits and attachments. Mr. Davis
advises us that we can expect to have further steps taken by TTAB,
under their complex procedural rules over the next few months.
TTAB will first notify Della Croce of the filing and permit him
time to respond, then evidence can be collected and depositions
taken, and then the parties can file briefs and other responses.
Often these cases take more than a year to be resolved by a TTAB
decision.
All of our industry is fully aware that Linus Torvalds developed
Linux and that it has become one of the world's most popular
operating systems during the past six years. The participants in
this proceeding expect the TTAB to cancel the registration, after
hearing and seeing the massive evidence demonstrating that Della
Croce had no conceivable legal basis for his claim to the mark.
The petition itself is available here and on the websites of each
of the petitioners and Mr. Davis' law firm at www.iplawyers.com.
We urge that interested persons read it, and distribute it and
this message to all members of the LINUX community so that they
will be aware of what is being done about this outrageous
trademark claim. We will try to keep everyone posted on
developments in the case through user groups and webpages.
We will continue to keep you updated on the happenings in this
action. Check the Linux Hot News Button for the latest updates.
_____________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Back Next
_____________________________________________________________
_____________________________________________________________
"Linux Gazette...making Linux just a little more fun! "
_____________________________________________________________
SLEW: Space Low Early Warning
By James T. Dennis jim@starshine.org
_____________________________________________________________
One of the worst things you can do to your linux or other
Unix-like system is to allow any of the filesystems to get full.
System performance and stability will suffer noticeable
degradation when you pass about 95% and programs will begin
failing and dying at %100 percent. Processes that are run as
'root' (like sendmail and syslog) will actually fill their
filesystem past 100% since the kernel will allocate some of the
reserved space for them.
(Yes, you read that right -- when you format a file system a bit
of space is reserved for root's exclusive use -- read the mke2fs,
e2fsck, tune2fs for more on that).
Considering the importance of this issue you might think that our
sophisticated distributions would come with a pre-configured way
to warn you long before there was a real problem.
Sadly this is one of those things that is "too easy" to bother
with. Any professional Unix developer, system administrator or
consultant would estimate a total time for writing, installing and
testing such an application at about 15 minutes (I took my time
and spent an hour on it).
Here's the script:
#! /bin/bash
## SLEW: Space Low Early Warning
## by James T. Dennis,
## Starshine Technical Services
##
## Warns if any filesystem in df's output
## is over a certain percentage full --
## mails a short report -- listing just
## "full" filesystem.
## Additions can be made to specify
## *which* host is affected for
## admins that manage multiple hosts
adminmail="root"
## who to mail the report to
threshold=${1:?"Specify a numeric argument"}
## a percentage -- *just the digits*
# first catch the output in a variable
fsstat=`/bin/df`
echo "$fsstat" \
| gawk '$5 + 0 > '$threshold' {exit 1}' \
|| echo "$fsstat" \
| { echo -e "\n\n\t Warning: some of your" \
"filesystems are almost full \n\n" ;
gawk '$5 + 0 > '${threshold}' + 0 { print $NF, $5, $4
}' } \
| /bin/mail -s "SLEW Alert" $adminmail
exit
That's twelve lines of code and a mess of comments (counting each of
the "continued" lines as a separate line).
Here's my crontab entry:
## jtd: antares /etc/crontab
## SLEW: Space Low Early Warning
## Warn me of any filesystems that fill past 90%
30 1 * * * nobody /root/bin/slew 90
Note that the only parameter is a 1 to 3 digit percentage. slew
will silently fail (ignore without error) any parameter(s) that
don't "look like" numbers to gawk.
Here's some typical output from the 'df' command:
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/sda5 96136 25684 65488 28% /
/dev/sda6 32695 93 30914 0% /tmp
/dev/sda10 485747 353709 106951 77% /usr
/dev/sda7 48563 39150 6905 85% /var
/dev/sda8 96152 1886 89301 2% /var/log
/dev/sda9 254736 218333 23246 90% /var/spool
/dev/sdb5 510443 229519 254557 47% /usr/local
Note that I will be getting a message from slew tomorrow if my
news expire doesn't clean off some space on /var/spool. The rest
of my filesystems are fine.
Obviously you can set the cron job to run more or less often and
at any time you like -- this script takes almost no time memory or
resources.
The message generated can be easily modified -- just add more
"continuation" lines after the 'echo -e' command like:
|| echo "$fsstat" \
| { echo -e "\n\n\t Warning: some of your" \
"filesystems are almost full \n\n" \
"You should add your custom text here.\n"\
"Don't forget to move the ';' semicolon "\
"and don't put whitespace\n" \
"after the backslash at the ends of these lines\n\n";
Note how the first echo feeds into the grouping (enclosed by the
braces) so that the contents of $fsstat are appended after the
message. This is a trick that might not work under other shells.
Also, if you plan on writing similar shell scripts, note that the
double quotes around the variable names (like "$fsstat") preserve
the linefeeds in their values. If you leave the quotes out your
text will look ugly.
The obvious limitation to this script is that you can only specify
one threshold value for all of the file systems. While it would be
possible (and probably quite easy) to do this some other way -- it
doesn't matter to 90% of us. I suspect that almost anyone who does
install this script will set the threshold to 85, 90 or 95 and
forget about it.
One could also extend this script to do some groping (using
various complex find commands) to list things like:
+ Who is the biggest disk hog (which user is taking up all the
space and what are his or her largest files)?
+ What are the oldest, least accessed files on that filesystem?
This last question could be answered using something like
'find -xdev -printf "%A@" | sort -n | head' --
which reads something like "find all the links on this filesystem
and print time that they were last access (expressed as
seconds since 1970) and their filenames; sort that and just
give me a few of the ones from the top of the sorted list."
As you can see, find commands can get very complex very
quickly.
I chose to keep this script very simple and will develope specific
scripts to suggest file migrations and deletions as needed.
As you can see it is possible to do quite a bit in Linux/Unix
using high level tools and very terse commands. Certainly the
hardest part of writing a script like this is figuring out minor
details about quoting and syntax (when to enclose blocks in braces
or parentheses) and in determining how to massage the text that's
flowing through your pipes.
The first time I wrote slew was while standing in a bookstore a
couple of years ago. A woman near me was perusing Unix books in my
favorite section of the store and I asked if I could help her find
something in particular. She described the problem as it was
presented to her in a job interview. I suggested a 'df | grep &&
df | mail' type of approach and later, at home, fleshed it in and
got it working.
Over the years I lost the original (which was a one-liner) and
eventually had one of the systems I was working with hiccup. That
made me re-write this. I've left it on all of my systems ever
since.
I'd like to encourage anyone who developes or maintains a
distribution (Linux, FreeBSD, or whatever) to add this or
something like it to the default configuration on your systems.
Naturally it is free for any use (it's too trivial to copyright in
my personal opinion; so, that there is no doubt, I hereby place
SLEW (comments and code) into the public domain).
_____________________________________________________________
Copyright &copy; 1997, James T. Dennis, Starshine Technical Services
Published in Issue 13 of the Linux Gazette
_____________________________________________________________
[ TABLE OF CONTENTS ] [ FRONT PAGE ] Back Next
_____________________________________________________________
_____________________________________________________________
LINUX GAZETTE BACK PAGE
Copyright &copy; 1997 Specialized Systems Consultants, Inc.
For information regarding copying and distribution of this material see
the Copying License.
_____________________________________________________________
CONTENTS:
+ About This Month's Authors
+ Not Linux
_____________________________________________________________
ABOUT THIS MONTH'S AUTHORS
_____________________________________________________________
Larry Ayers
Larry Ayers lives on a small farm in northern Missouri, where he is
currently engaged in building a timber-frame house for his family.
He operates a portable band-saw mill, does general woodworking,
plays the fiddle and searches for rare prairie plants, as well as
growing shiitake mushrooms. He is also struggling with configuring
a Usenet news server for his local ISP.
James T. Dennis
Jim Dennis is the proprietor of Starshine Technical Services. His
professional experience includes work in the technical support,
quality assurance, and information services (MIS) departments of
software companies like Quarterdeck, Symantec/ Peter Norton Group,
and McAfee Associates -- as well as positions (field service rep)
with smaller VAR's. He's been using Linux since version 0.99p10
and is an active participant on an ever-changing list of mailing
lists and newsgroups. He's just started collaborating on the 2nd
Edition for a book on Unix systems administration. Jim is an avid
science fiction fan -- and recently got married at the World
Science Fiction Convention in Anaheim.
Bill Duncan
Bill has worked with Unix systems since the early Version 7 days on
PDP-11's. He worked with Xenix throughout most of the eighties and
has also worked with many other flavors of Unix over the years,
but his operating system of choice is now Linux. When not working
or fiddling with his four Linux systems at home (which is rare),
he might have some time left over for his other hobbies; his dog
(Daisy), photography and Amateur Radio.
Michael J. Hammel
Michael J. Hammel, is a transient software engineer with a background
in everything from data communications to GUI development to
Interactive Cable systems--all based in Unix. His interests
outside of computers include 5K/10K races, skiing, Thai food and
gardening. He suggests if you have any serious interest in finding
out more about him, you visit his home pages at
http://www.csn.net/~mjhammel. You'll find out more there than you
really wanted to know.
Oleg Machulski
Oleg Machulski is a student of Laboratory of Computing methods at the
Faculty of Mechanics and Mathematics, Moscow State University.
He has been a Linux enthusiast since Sept.1996 as well as an OS/2
enthusiast. After receiving the source of a very unusual DOS text
editor, where the program was structurized in a hypertext manner
from his scientific advisor Andrey V. Astreling, he wrote and
ported the following functions: search, macrocommands, multiple
pages and so on. Brief history of that freeware project could be
found at http://shade.msu.ru/~machulsk/mmm/mmm.html Also, I like
to play guitar and listen to jazz music. Additional info can be
found at my homepage http://shade.msu.ru/~machulsk
Hans Paijmans
Hans "Paai" Paijmans is University lecturer & researcher at
Tilburg University and a regular contributor to several Dutch
journals. Together with E. Maryniak he wrote the first dutch book
on Linux--already two years ago. My, doesn't the time fly. His
homepage is at http://pi0959.kub.nl:2080/paai.html.
Greg Roelofs
Greg Roelofs, aka Cave Newt, is best described as a phenomenon, as in,
``Captain, we're picking up strange readings from that unexplained
phenomenon over there.'' Greg's job description is appropriately
schizoid, given his interest in far too many things for his own
good. He's a full-time researcher in
multimedia/image-compression/WWW stuff at Philips Research at Palo
Alto, having made the switch from Unix system administrator in
August 1995. He likes to fancy himself a software developer; among
other things, he has been a member of the Info-ZIP team for six
years and the principal author of UnZip for most of that time.
(He's also a member of the Portable Network Graphics Development
Group and the maintainer of the PNG and zlib home pages.) As for
recreational interests, he likes to amuse himself by cycling
(often to work); skiing--any flavor, although snow preferred,
especially if it means he can drive in it; scuba diving--for 18
years now, from the shores of Lake Superior to the coast of
Venezuela to the kelp beds of Monterey; and hiking/backpacking,
particularly in the Sierra Nevada range; and amateur photographer.
James Shelburne
James Shelburne currently lives in Waco, Texas where he spends
most of his free time working on various Linux networking
projects. Some of his interests include Perl + CGI, Russian,
herbal medicine and the Ramones (yes, you heard right, the
Ramones). He is also a staunch Linux advocate and tries to convert
every MacOS/MS Windows/AMIGA user he comes into contact with.
Needless to say, only other Linux users can stand him.
_____________________________________________________________
NOT LINUX
_____________________________________________________________
Thanks to all our authors, not just the ones above, but also those
who wrote giving us their tips and tricks and making suggestions.
Thanks also to our new mirror sites.
I'd like to apologize for being later than usual getting LG
posted. The weather in Seattle has been a more than a little
bizarre lately. My neighborhood got about 20 inches of snow from
December 26 to December 29. Since the normal yearly snowfall is
about 4 inches, everything stopped, including the buses for the
first time in Metro history. SSC had a portion of the roof give
way under the weight of snow and water (the rains started December
29 and haven't quit yet). As a result of the flooding, things are
in quite a mess around the office. Yearly rainfall in Seattle is
usually 31 inches; this year we had 55 inches. I thought I was
back in Houston!
Actually, I was back in Houston during my vacation week before
Christmas. The weather wasn't great there either -- rainy and
cold, and I was counting on sunshine. However, I still had a good
time visiting with family and friends. My grandchildren, Sarah and
Rebecca, are a delight to be with -- I miss them a lot.
Have fun!
_____________________________________________________________
Marjorie L. Richardson
Editor, Linux Gazette gazette@ssc.com
_____________________________________________________________
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